I do agree on it being kind of silly to debate over what counts as a videogame and what not. Stuff like Dear Esther is being called a game as well, because, to be honest, nobody wants to use terms like "interactive digital-virtual narration and fictional space experience simulation" on a regular basis - deal with it, it's just a word. It doesn't kill the other games by being called one.
I also think they are entitled to create whatever they want and there seem to be enough people who enjoy it. I cannot play Dear Esther, because it doesn't run on my PC, but it does sound like something I would enjoy, too.
The problem comes with making a sequel to a game that people loved for what it was. There are expectations to be met. I haven't finished AMFP yet, but I can already see the difference and it's not for the better, even when the game has its own merrits.
To me, an important part of horror games is the (even if just theoretical) possibility to do something wrong. Go into the wrong direction, approach a monster when you should've fled ect. I know, in the end, with checkpoints and savefiles, what does it matter, but while you play, not knowing what lies in what direction or what action will result in what outcome is a strong feeling that builds dread.
Even when it's mostly clear what you're expected to do or where you must head, a good horror game is about doubts. Should I really go there or should I check out this hallway over there? Or maybe it's not save there. All of this need not necessarily be a conscious line of thoughts, it can and probably should happen subconsciously.
A very good example is to be found in Silent Hill 2. At certain points in this game, you will have to ... proceed somewhere, to keep it spoilerfree, and the game stops you and asks you if you are sure you want to go into that room. You, as the player, know it's the correct path, but the mere question, are you sure, reminds you you're actually not. It appeals to your doubts and inner wish to not move on. And so going on feels more threatening than it aleady did before you were asked.
What a good horror GAME needs is doubt. Insecurity. The feeling that you can do it wrong. It must give you opportunity to feel lost in its world.
AMFP, on the other hand, is too linear and doesn't even offer sideways to explore. The doors, drawers and wardrobes are locked and you can see it without even trying to open them. You literally cannot get lost and there's no deciding about how to proceed. Since there isn't really much to do besides walking on, you cannot feel like you might fail.
And that's where the game fails, in my opinion, as a game. I think it is spooky and has lots of atmosphere, but that can be true for a movie as well. It fails to make me part of it. If CR like to create games in which you are basically reduced to a spectator, that's fine, it tells a story, it sets a mood, it gives you stuff to look at and listen to. No prob, I can enjoy that, too.
But if said game is a sequel to a different experience, they should be able to understand why people are disappointed by what they got instead of pretty much calling the others ignorant.