Actually the overall quality of the animations are way better then any TW game, only thing they removed was that all units had kill animations(very few still has unique kill animations). As a Warhammer fan I can tell you that CA put alot of effort into those animations to get the units to move and attack as they should and they nailed it and it looks beautiful. The sight of a Gorebull charging into a unit of infantry and doing so by jumping into them head first is glorious.
And let's remove the rose-tinted glasses, 60% of the time in RTW2 when two infantry units were fighting, they were just swinging their weapons randomly in the air and someone dies. Kill animations were not that plentiful and most of the time you never saw them to begin with but they did have an effect on performance. This is why I can imagine few people were upset over the removal of the kill animations, it wasn't a big deal to begin with.
I had no problem either with 20 vs 20 in Rome or Attila but most of the time I never fought 20 vs 20 since the AI usually had 2 full-stack armies next to each other which meant that I had to bring 2 full stacks as well, now we are starting see battles turn into slide-shows.
Warhammer has the same thing even tho I would say that 20vs20 are more common but larger battles then that are still plentiful but despite having better graphics and alot more special effects going on due to artillery, gunpowder weapons, spells going off and all that, I can play 40vs40 with no performance hit.
So if you give me the choice of smooth large battles with kill animations over smooth massive battles without kill animations, I will take massive battles any day.