In my opinion, the backlash and hate behind RE6 is caused in part by the two different branches of RE fandom finally uniting together.
There are, generally speaking, two main factions of RE fans; those who preferred the straight and generally serious B movie horror, and those who preferred the more action focused tongue in cheek B movie horror. Not to say you couldn’t enjoy both; but most people had a preference and a lot of people really didn’t like the other option.
If you were camp serious horror, then everything from 4 on was RE getting away from its roots and becoming something it never should have been. RE6 was just more of the same AND they even taunted you up front with the idea that this was at least partially going to be a return to form of pure horror in sections. For people who liked the action side of things, which I personally tend to favor, RE6 took everything that made 4 and 5 so playable, and absolutely flubbed it.
I can fully understand not liking 4 and 5, I can completely get why people would not want to play what to them felt like a completely unresponsive third person shooter. What I can’t understand is people who say the game plays poorly.. Whether you love them or hate them, 4 and 5 are balanced perfectly for their controls. Someone who knows what they are doing can flow shooting, melee attacks, crowd control, reloads, everything, into long unbroken streaks. Everything is intentional and considered, and you always know how your character and the enemy is going to react. I know what enemies I can suplex, which will fall to their knees, which will trip over entirely, etc. It is a known quantity with many options, all of which are simple to execute but give you countless opportunities with your verbs.
RE6 takes this design of simple execution and predictable results, and dumps a metric ton of random bullshit onto it. Look up a guide to melee combat in RE6 and you’re going to find a small novel that feels like it was barfed up by an early alpha of an AI text bot. Attacks are now based on character, weapon you’re holding, how close you are to a wall, how close you are to a ledge, whether the enemy is aware of you, enemy position, CAMERA POSITION, the list goes on. I played through all of RE6 and I never once felt confident in what my character was going to do. Was I standing in the right spot to get a critical hit on this ground stomp or am I going to whiff? Am I facing the camera enough for this to count as a back attack or will I swing forward at nothing? Can this enemy be countered at all, is it doing a counterable attack, am I in the butte zone to actually allow me to do that? It took the fine tuned gameplay of 4 and 5 and made it a clunky, unpredictable mess.
So RE6 became the game for no one. It satisfied neither camp with the only true horror the game provided being the unbearable tension of seeing what your button inputs would actually do. It was scary, it wasn’t tense, and it wasn’t fun to play.