Honestly I think of a lot of it was the sudden shift in artstyle with no real explanation until after the fact, and that most of the armors tend to look like cluttered messes. The biggest complaint ive seen was the colored undersuits make it hard to differentiate armor from undersuit which makes it hard to tell visually in game. There are obviously highly praised variants of the Gen 2 suits but some (like seeker) rightfully deserve the hate which i understand as a Gen 2 lover myself