I agree with this, but I think it's a failure of the army design, not necessarily the setting. For instance, I've always thought it would be nice to be able to field a peasant infantry army. Hell, they don't even have a Man-at-Arms hero, which seems strange to me. Furthermore, the Knightly characters must be fielded as cavalry unless you pay points for the Virtue of Empathy, which I believe is multiplied in cost every time it is taken by an additional character.
That's true, but I think the question of distinguishing Bretonnia from the Empire, or for that matter other armies like Chaos, is still a valid one. If I can make a Bretonnian army with a hard core of elite foot knights, supported by cheap men-at-arms and yeomen and a few magicians or ethereal creatures from the Lady's realm, isn't there a risk that it will play very similarly to the Warriors of Chaos? That similarity would ultimately hurt
both Bretonnia and Chaos, because each faction's unique play-style is essential to establishing its character.
So while we might want more diverse strategic options for Bretonnia, we also need all those options to
feel Bretonnian. We see this with the Empire, don't we? An Empire gunline and a dwarf gunline still feel different, and it's not just because the models look different or because there are different background descriptions in the book. The units you can take and their unique stat-lines make the armies play differently. Similarly, Bretonnia and the knight-heavy Empire army also play differently. Sure, they both consist almost entirely of mundane humans in heavy armour on horses with lances, but they feel different: rules like the Blessing and the Lance change the way the Bretonnian player has to respond to threats, and they create new strengths and weaknesses, while the fact that the Empire knightly army can stick in a few mounted warrior-priests with bound prayers or have the advancing knights supported by a steam tank add a different flavour. Even if we played our games entirely with little scraps of paper with statistics written on them, there would be a discernible difference.
Therefore, when I think about diversifying the army, the question that I find I have to grapple with is: "What feels Bretonnian? What features would make an army feel like it's from Bretonnia? What makes Bretonnia unique, and how can I represent that mechanically?"
The most appropriate armies for comparison would be Empire and Warriors of Chaos, right? The other human armies. What do I get if I think about them?
Consider the Empire. The flavour of the Empire is a diverse and fractious human realm, united (and occasionally divided) by religion, often somewhat paranoid and prone to internal conflict, with advanced technology and a love of gunpowder. It is particularly inspired by the Holy Roman Empire, perhaps in the 16th century or during the Thirty Years' War. The soldiers of the Empire are often physically inferior to their foes, but compensate through cunning combined arms tactics. So when we look at them on the tabletop, there's a pretty wide variety of units. Empire units tend to have pretty mediocre stat-lines, but their detachment rule simulates their cunning tactics. They use ranged weapons and war machines to keep enemies at arm's length and soften them up before it comes to combat, representing both their physical inferiority and their love of technology. Characters are diverse and eclectic: wizards, warrior-priests, witch-hunters, etc., all represent different organisations and have to be used in different ways, reinforcing the nation's internal tensions. Witch hunters don't like wizards. Engineers have quirky and unreliable weapons. Religion is a major driving force. And so on. The army book does a good job of turning the Empire's diversity into a strength and letting you get a sense for what the faction is like.
I won't do something similar for Chaos because I've never had a Chaos army. But you could do the same thing. Chaos is all about inevitability and power, the coming doom of the world at the hands of the Ruinous Powers. They ought to
feel strong. So they have very powerful characters. Chaos's flavour is centered on the four Chaos gods, so Chaos units usually come in four different flavours. Chaos has both rock-hard elite infantry to help make them intimidating - the dark tide from the north has to be strong - but they also have cheap marauders because they should be a horde. Rules like Eye of the Gods help communicate their arrogance and power, as they believe they are invincible, and the occasional randomness this rule injects helps make the gods feel capricious. But it also makes the gods feel present and it makes them feel attentive, since the Warriors of Chaos should feel like they are marching under the gaze of their gods.
What could I say about Bretonnia in that light?
Well, Bretonnia is another human realm, perhaps better united and not riven by as many internal disputes. It has a single dominant religion and tends to reject high technology. Bretonnia has a very heroic ethos and loves the quest motif. Bretonnia is particularly inspired by Arthurian mythology and British and French folk-tales or fairy-stories, as opposed to the Empire's more historical feel. How can these things be communicated mechanically, while still feeling different to either the Empire or Chaos?
In some ways I think the current list does very well. The Blessing of the Lady is an excellent mechanic, for instance. Bretonnia is religious, but it is not religious in the same way as the Empire: its spiritual power is not primarily vested in particular characters, priests who channel their deity. The Lady is always watching her followers, and they try to prove themselves worthy of her favour. But this is also different to Chaos, because the Chaos gods are very fickle, and the Eye of the Gods rule is absolutely focused on individual characters. The Lady blesses the entire army, and her blessing is not random in any way. Rather the Blessing is a favour given for Bretonnians trying to live up to a particular code of behaviour: so there are mechanics for gaining the blessing (if you pray for it, demonstrating your desire to follow it) or losing it (if you fail to live up to the code).
It's actually kind of impressive when I think about. The Empire, Bretonnia, and Chaos army lists all use mechanics to give the feeling that these armies' gods are watching and helping, but the mechanics have been carefully chosen. The Empire has a historical feel with powerful conflicting religious institutions, so it has priests with special powers. Bretonnia has an omnipresent goddess with a strict code of conduct, and they get bonuses if they follow it. Chaos has capricious and nasty deities that unpredictably reward great deeds. It's all done quite well.
Anyway, what else...
Because Bretonnia has a heroic feel, it understandably emphasises its characters, but in order to feel properly heroic, they should also feel like underdogs. The knight is the underdog when he fights the dragon; Jack is the underdog when he fights the giant; and so on. So Bretonnian characters have pretty modest stats: they're decent, but they are still humans. That said, they also need ways to win their fights. An expanded or rebalanced Virtue system might help a lot.
How else can you make Bretonnia feel heroic? Bretonnia should probably be aggressive, and get to grips with the enemy quickly. Heroism is dynamic. Most of its units should be capable of fighting; tarpits and sacrifices and the like don't have the proper feel. All armies need expendable units, but Bretonnia should handle its expendable units carefully. Knights fit this goal pretty well: they fit the Arthurian theme, they are quick and strong, they can be aggressive, and they're valuable enough that you don't want to lose them.
The units you've listed are quite good in this respect. I'm not sure about priests, but healing or protecting magic fits the theme, and I really like the idea of a bard or troubadour hero. Storytelling and inspiring people really fits with the Bretonnian aesthetic, and it's something that no other army does at the moment. I also really like the variety of mounts. A few different types of 'heroic' monsters would fit Bretonnia quite well: what is Bellerophon without Pegasus, or Ruggiero without the hippogryph? We could also include the occasional hero-monster outside of character slots; perhaps a Questing Beast or a peryton or somesuch. It also feels like there is a rich vein of imagery to mine elsewhere in Western European heroic folklore: Robin Hood, Robert the Bruce, Joan of Arc, and so on. That could help diversify Bretonnia a bit more, in terms of imagery and culture.
