I don't speak for Apple but IMO, this was primarily due to the so many PCs not having a Firewire connection.
Does your iMac not have a USB 2.0?
I and many others agree about the loss of Firewire support but the following was copied from another thread here on this subject.
480Mb copied from iPod:
USB 1.1 - 11 min 15 seconds (G4/1GHz)
USB 2.0 - 2 min 44 seconds (G5, 2.0 dual)
(for comparison, the same folder copied in 2 min 18 seconds via FW from my 3g iPod)
In this experiment, USB 2.0 was only 26 seconds slower than Firewire to transfer 480 MB so the transfer rate using USB 2.0 is not extremely slower than using Firewire.
I don't believe there is a way to use a Firewire cable to transfer data with a new iPod.