I have to clarify something here. NT 4 does not support booting from software raid 0(striping), and neither does 2000 or XP. Booting from a software mirror is always supported, but only windows servers support software mirroring, not workstations or pro. So it is not ridiculous, and no functionality with respect to this has been lost.
It really annoys me that 200 pro and XP pro do not support disk mirroring, and only the servers do. With the cheapp prices of hard drives, it would be a great way to keep them workstations running.