Norm or not, exactly how many people simply decide to add $1000-$1500 worth of upgrades to their computer? In the past two years I've had my computer, the only money I've spent on it has been $150 for a new graphics card when BioShock came out. But there's no way I'd spend ten times that when that money could be better used on many, many other things.
The point is that Crysis advertised a level of graphical quality that the majority of computers simply cannot acheive. Are you required to play at that level? Of course not. Does everyone who bought the game want that level? Hell yes. Is everyone capable of that level? No, and that's the entire problem.