Do people realy care about the story in custom storys?

[Cranky Old Man]

It depends on how good the environments are.
If you toss a note in a corridor, and it's actually five pages long of badly formatted text about what you ate last week, then nobody's going to read it.
If you have the player trek through a golden palace to arrive at the head desk, then you've given the players head time to fill with questions like "What's this place all about?" and "What's going on?", and if you then present him with enough exposition to satisfy some answers, but keep him wondering about it, then (at least intelligent) people will be intrigued enough to think about the story.

In Amnesia, the protagonist has just lost his memory, staggering around, wondering what's going on. This is what the player is wondering too. Who he is can wait until the basic gameplay controls and horror, has been presented. THEN a simple long-term objective is given. It COULD have explained more right there, but it didn't, as that would have left nothing for the player to wonder about later.

My rule of thumb is to let the maps explain as much of the story as possible: Visual explanations and sometimes audial explanations, takes less effort from the player to understand than written explanations.

Final tests of a players understanding of the plot can be given, that he must pass in order to proceed. They might be as simple as "PS. I've hidden the key behind the painting." and they may be very deep, like preparing a room according to the mind of a ghost of a serial killer.