Don't agree....the only reason why lately many FPSs have good graphics is just beacuse is the most popular genre in the west...there are a lot of non-FPS to have great and better graphics... ResidentEvil5 on PC, for expample looks better than any fps game you have listed (apart from Crisis2, which I haven't seen yet).

Short linear games usually have good graphics.

because they are the easiest of all games to make. Much less coding and work needed to make a first person game period so they can use more time and know how getting the graphics to look better.

I always felt the bulk of first person shooters were very ugly. I still find SNES titles more eye-pleasing than a lot of colourless FPS titles we get today. High polygon counts don't always make things better.

Except for Crysis and Killzone 2 I don't really know FPS who are supposed to have best graphics.
Best looking games on console at the moment are Uncharted 2 and God of War III, and these are not FPS...

First person view is the closest thing to our reality which is why we know exactly how to implement graphics upon it. Third person is getting there but not quite. We can relate to how we see things infront of us so its easy to put that in a game compared to other perspectives.

you are in direct control of the camara so it has to look perfect at a close range.

they r restricted thts why