I think the point is that RE4, while wandering a bit from the the well worn path followed by every other main RE game, still maintained some level of tradition in the series. RE5 takes every one of those non-traditional aspects and brings them even further from the standard formula.
As a mediocre analogy, think of the Metroid Prime series. The first game was clearly radically different from the previous Metroid games, yet the game remained true to the "Metroid Experience" in many ways. The "spirit" of Metroid was still there, if you will. However some people still complained about it being a "first person shooter." Then Metroid Prime Hunters came out and took those differences the Prime series had from the previous game and multiplied them. Due to the system it was on, it now controlled like a FPS, and now there were other competing bounty hunters in the game. Then MP3 came out and maintained the FPS control scheme while adding even MORE characters, like the soldiers and whatnot. Every step the series took wasn't radically different from the game before it, but then all of a sudden you compare MP3 to Super Metroid and there are some huge differences. Of course, most people didn't mind the differences, but you get the point. The game changed in relatively minor ways with each iteration until the most recent game is drastically different from the first.
Anyway, what I'm getting at is that all of the things in RE4 that made it more of an action shooter are now even more prevalent. So while RE4 still had the "spirit" of the old games, RE5 does not. Of course, a lot of people blame the environment for a lot of those feelings which just isn't a strong argument, seeing how this is only a two level demo.
Anyway, I haven't played any RE game BUT 4, including this demo. So I should go now.