He's a really big guy and that's probably the one thing holding him back now from running in the 9.4's.
I actually disagree with you there. I think his size is what's making this possible. He covers so much ground with each stride that a shorter runner's turnover would have to be dramatically faster to keep up. The one potential downside of his size is unfurling that full frame out of the blocks - you might think a shorter, more compact runner would have an advantage there. But since Bolt pretty much won this race in the first 30m, I guess that theory's out the window.
Also - he won his 200m heat in 20.70. 1.4 sec. off his WR and still good enough to win a heat at world's!!