I think a good game is a sum of parts that are a little more complicated than that. Being obtuse doesn't do RE6 any favors, but to someone who can break games down by thinking about them, the level of complication RE6 challenges the player with is relatively small.
As for some of the particular problems, like quick-shooting dogs... should the game say "Dogs are weak to quick-shot"? Maybe when you first encounter one? To me just finding out what a quick-shot did was enough for me to figure out what was the best situations to use it in. Dodge is a dodge, so maybe it isn't a leap to dodge distant and predictable lunges. There definitely should have been a good tutorial, but at some point (hour 12, maybe) you have to shift some of the blame on the player. At least if you do when you are capable of seeing how that player is messing up.
EDIT: Giving contextual melee a shared button with the raw melee does seem like a mistake. RE5 simply didn't have that problem with the knife, for example.