That first video
Shocking some of the... laziness?... in there. For some reason, the balls disappearing into the walls in the latest one compared with the original (around 8:30) left me most surprised. As well as not being able to pick up the sports equipment to use as a weapon.
What's 3 like in that regard? I can't really remember.
It's probably a tradeoff between number of zombies and the environment that can be supported. I guess they went for more zombies.... which seems to have really detracted from the rest of the things that made the first game fun/involving.