That's partly because USB 2.0 was at the time a competing standard of sorts with Firewire. And Firewire still outperforms it, in all fairness. It wasn't in 's best interests for USB 2.0 to gain traction over firewire and for users who needed the speed of firewire, USB 2.0 was a bum deal.
I would say that this sort of thing won't happen this time around, except that Light Peak was announced, and I don't think anybody outside of or Intel has a handle on the ramifications of it yet.
Fact: There's more to an emerging standard than specifications. Before release, you have no way of knowing whether or not the hardware will meet or fail to meet specs or expectations. USB 2.0 is theoretically faster than FW 400, but never outperforms it.