Yes, sure, you are probably right. Lets not fret over the small things.
One thing I would definitely like (from simply a no brainer, just for fun and fluff reasons) for any/all characters in an army to have a common mount selection.
For empire:
griffin, demigryph, warhorse, pegasus.
This would allow you to take a warrior priest on pegasus if you really wanted to, or a captain on a griffin, or a grand master on demigryph...
As long as every army gets the same thing, why not? And of course making some exceptions where necessary (Warlock engineers should not be able to ride a screaming bell... or should they? IDK).