I agree with all your points outside of Mr.X, zombies and difficulty. I personally thought they were a huge improvement over the original. I know you're just stating criticisms of how they could have been better I just meant in terms of what wasn't improved on the original. To me those were. EVERYTHING else though I couldn't agree more. I like the look of the lab to an extent but it felt a bit streamlined and lost it's grit.....I know the lab was supposed to be newer but it looks TOO futuristic.
The thing with Mr. X is he was an event in the original. It was fresh and new for RE. Now he's just a mild annoyance. It's not like Nemesis who's a real threat with the game structured around him which adds some immediacy to everything. Mr. X really needs to spawn in a room with Lickers to really matter.
Zombies were a joke in the original too but I'll still take learning enemy layouts and behavior patterns over just popping a few leg shots and running again and again. Dodging them was just more satisfying is all. REmake2 really only has handful of tricky jukes and the adaptive difficulty/leg shots makes them far less vital than they should be.