That's true.
USB is "host controlled" meaning your CPU has to do some of the work. Whereas firewire hardware has it's own CPU (or something) internal to the device. You can also chain some firewire devices one off each other (i.e. the MAC keyboard is connected by firewire and has 1 or 2 firewire ports on it too)
USB devices are generally cheaper for these reasons, also easier to manufacture.
I've never managed to get the theoretical max USB 2.0 speed (~50mb/s) anyway as the devices I'm using are never that fast (HDD, flash drive, camera) but there must be some device out there that is pushing the boundary?