Having a fat friend is cool. You don't have to worry about him stealing glances from women, and you can be sure that your girlfriend will never cheat with him. Fat guys are so cool, especially if you're not fat.
Imagine hanging out with your fat friend and a hot girl comes walking by. You can use him as ramp to show off your freestyle swag. It's easy once you realize that she never had her eyes on him. He was always meant to be the guy in the middle, the one who listens in and remembers the details just in case you forget while staring at her rack.
No, I don't think that's what's going on. What I think is happening is that mainly TV is starting to realize that not everyone needs to be a set bodytype to be on TV. Still the place where you'll see fat people is more often than not, a sitcom. So I don't think it's a whole LOT of progress, if any. It might just be some group of A-Holes running the networks who think "hur hur hur... Fat people are funny." or something equally retarded.
All in all who the hell knows. But I don't think fat people are the new cool thing.
Being fat isn't cool or uncool. It just is. Guys like Kevin James and such are just good actors. A lot of those guys are popular due to self-deprecating comedy or the like. Everyone loves making fun of the fat guy. It's good t.v. Apparently. I'm indifferent really. But don't underestimate someone because of their weight.