Re: Crysis
Invisible optical camo first entered the public consciousness back in the 80s with Predator. And again in 1995 with the movie Ghost in the Shell, which came from the manga that began being published back in 89. So saying MGS4 and its innovative visible adaptive camo system "copied" Crysis is a a bit silly considering the optical camo concept was used by MGS2 (predating Crysis by six years) and again in MGS3.
And as for why Peace Walker is showing up on PSP as opposed to the PS3, I'd have to say it's probably a development time issue as much as anything else. While Kojima could do a PS3 MGS5 using the MGS4 game engine, any non-reused resources (models, textures, levels, vehicles, weapons, etc.) would still have to be highly detailed as opposed to the sub-SD art resources of a PSP game. So it boils down to being able to get the finished product to the consumer faster not that this was the only reason for the decision.