I agree about most home studio guys can use either FW or USB. Especially USB 2.0. 99.9% of the time, they will work equally well.
Correct me if I'm wrong, but it all started from the PC vs MAC thing. Apple developed FW and the IBM/Intel guys developed USB. Eventually, PCI cards came out for PC's so you could use FW devices with them instead of a Mac.
From what I read recently, FW is dying out because the video camera manufacturers that originally used firewire have been migrating to USB. USB is becoming very universal. From keyboards to cell phones, to the goofy LED lamp I have over my mixer!