And the console versions proved that the consoles were more or less able to keep up and put out a game like that. It wasn't a PC exclusive because it was exclusive, it was PC exclusive because Crytek's optimisation was god awful for that version of CryEngine.
I don't think that's a fair criticism. Crysis was a new engine, pushing the boundaries of gaming graphics. It has been beaten since, but it took other companies another few years to manage it.
It's just like the xbox360/PS3 generation: now, developers can get a lot oiut of those machines, thanks to all the tricks and techniques that have been learned over years. But when they were first developed, they were much more poorly optimised and capable than they are now.
Just like GCN: AMD's drivers massively improved performance in a bunc of games, once they figured out how to get the best out of GCN, a process that took many months.
Even so, I was just rereading a comparison of Crytek's console release of crysis and the pc version shows it still isn't clearcut: the new engine has some cool lighting tricks, the old one has some shoddy texture, but still the console version needed to be run at a cut down level.
Crysis was not a shoddily optimised game: it was a game that used new technologies and demanded powerful hardware to run at its best. The developers have learned ways to improve its performance, but also hardware in PCs has massively improved since then: try running crysis 2 on hardware that was around at the time of crysis release - I expect some of those optimisations they've developed will make it scale a little better to low end hardware, but in doing so, it won't look as good as crysis.