Things have improved by now, but my experience with the earlier USB 3 devices is that compared to their FireWire counterparts they were extremely flaky — wildly inconsistent transfer rates, intermittent disconnections, and general weirdness, especially for sustained workloads. I could see FireWire being preferred over USB 3 for that alone, even if USB 3 was faster on paper.
My experience with Firewire was that not a single peripheral I owned was compatible. So yeah, I probably would have preferred a few more USB ports instead of a dedicated plug for the iPod I don't own.
