AA diversity -
While more diversity would always be nice, we just can't do everything at once as long as there are other and more important things to be done because we have limited capacities.
As second reason, diversity needs to have some more of a concept rather than "make all stats different", which can quickly lead to diversity on paper but not make any difference in the game, which just makes the game harder to learn. (Which are ironically exactly the objections blodir has about the HP changes
) This happened to some degree with the static t2 flak, that is different now, but the differences are too small to be really impactfull or noticeable, they probably needed to be bigger, which both increases the amount of work to keep it balanced (reason 1) and the amount of people who will dislike the change (reason 3)
As third reason, even if we had the workload, too much change at once can be bad, as we can see by the wishes to split the patch already. And adding faction diversity like you suggest is always an uphill battle and provoces many angry forum posts and opinions, with more or less valid arguments, similar to the reactions about the HP changes as well. Long time ago (3 years maybe) i proposed to make bombers more diverse too, and this patch would've been a good opportunity for this aswell. But this things need to be done with care, time and patience, else the game can become too different from the original very quickly.
As result, my idea about balance is that when changes are done, they should try to preserve or increase faction diversity as secondary goal, but while changes that are solely done to increase faction diversity are not nececarrily bad, they shouldn't get out of hand. We add a lot of diversity in this patch (mostly in part 2 with the hp changes) already, lets not rush things.
However, interesting that you mention more range for aeon t1 maa, because it will probably happen in part 2 of the patch indeed.
But it will happen in line with what i wrote above, with the main purpose to nerf aeon a bit, and only using that as opportunity to increase faction diversity as seconday purpose.
Engies -
You already mentioned it, they can't be more efficient than t1 engies. They could have more bp and more cost, but that would be just as much of a disadvantage as an advantage. And as Hives and Kennels are not too much of an advantage right now, the compensation isn't badly needed anymore either.
