Most of the HW MorphOS supports does have a FireWire connector. No-one is forced to use FW and people can keep using USB2 if they like. At least I welcome an easy way to quickly connect a Mac to a MorphOS box and have access to the HDD (Target Mode). USB2 can't do that, unless if I open the Mac, remove the HDD and place it to a USB enclosure.
Sure you could use smbfs but samba is slower than firewire, and there are quite a bit of setting up to do, unlike with this firewire target mode.
I bought a device that can be used to connect 2.5" and 3.5" SATA HDDs in various ways. Connectivity includes USB2, FW400, FW800 and eSATA. Out of these USB2 is clearly the slowest. Now I have an option to use firewire as well.