Philly, sometimes I think you are too limiting when you say that something is "too" good to pass up, be it cannon or treeman. When something is that, you may infact wonder if it is not a bit... sniff, sniff... Rochfort...
However, I do not think the cannon is cheese, but It do seem to limit Empire players since all you hear is "take a cannon, no take two!"
That way, you will never develop and find other efficient and equally good setups for an army. Making yourself belive that something is "mandatory" will limit you in the end, and it is taking the short route and works toward streamlining and making everyones army looking the same.
A good gamer is happy to just shove aside the unit everyone tell him to take "because you have too", since then that model may be an obstacle to develop a deeper sense of tactics and for the game. And you will nerver challenge yourself to seek new ways.
Some of the finest generals became well known, because they could seemingly do lots with "nothing". Sure, many had some pet unit or tactic, but the bottom line is that some commander could do without seemingly "must have" stuff and might thereby find new ways to approach problems.
That some units preferred by great generals achieve fame and elite status, may not always have to do with them being much better or necessary for the general to win. It could simply be that humanity has a tendensy to follow the rule "If it ainīt broke, donīt fix it!". It is a good rule, but if you never challenge it, you may get blind for change and new ideas.
Alexander had his companions and used them as the hammer in all the battles. Still, you do get the feeling he could have done without them if needed. But they where his companions and he knew them personally and they where sworn to him. So he fought with them.
Caesar however, had his famous Ninth legion, but he shifted his own position from situation to situation. At Alesia, he stayed with his german cavalry and rode with them, their swift regrouping being instrumental in enabling the romans to hold the siege lines against the double assault.
On other occasions, he rushed in beside his legionnares or rode with other cavalry units such as the batavians.
Napoleon was a flexible mind, but in the bottom, he was an artilleryman, and his skilled use of artillery settled many of his battle. Still, he knew the rest of his force, but the artillery was what paved the way to victory.
Wellington was a infantrygeneral, and he rellied upon his redcoats more than anything else. By protecting his redcoats using ridges, he preserved them form Napoleons bombardment, as Napoleon himself observed.
Had not Blucher come to the aid, Napoleon would most likely have prevailed through having a slight advantage in number and a more cohesive force, and maybe because he was in the end a bit more flexible.
Wellington, the hero of Waterloo, would for a long time work against the modernization of the british army, clinging to his redcoats and their drills of line and square, meaning the british army got more and more out of time. I wonder if Napoleon would have been as blind?
Anyway, I say this. If you think that one unit is a "must" put it away and look think carefully. Are there infact other ways to get the same outcome as if you had cannons? Or a treeman for that matter.
Sometimes I do think some unit are too good without them being cheesy because of that, because they offer the straight and simple solution.
How would it be if weather had a stronger position in the warhammer battle? Would we see a somewhat less reliance on cannons?
And the fact that flaming is in the rising, and few armies bar the HE have anything that can really protect against it, the WE trees looks like they may become more threatened. I say it is about time asrai players find new options for the treeman and loads of dryads. It is hard to do, since the HE now almost force you to take such units, but at the same time, rellying upon them can turn disastrous after a few more armybooks.
The cannon is safe however, since it never rains in regular warhammer. A shame, it would have been lovely if there was an option for the gamers to try and influence the weather, representing attempts to try and engage your foe under more favourable conditions for your army.