Forward compatability, a practical guide
If, in Linux 2.4, the sequence
echo remove-single-device x y z > /proc/scsi/scsi echo add-single-device x y z > /proc/scsi/scsiactually works because the marked-as-pre-beta code won't let you remove-single-device the disk containing an active filesystem, don't assume that the no-longer-market-as-pre-beta 2.6 version will work the same way.
Because it won't.
The sysadmins might whine that "butbutbut we NEEEEEEEEEEED that feature and it used to work!!?!™", but when it gets right down to it the Linux core team doesn't care about your needs when it gets in the way of the 10 commandments of Unix (all of which are "The computer hates you") and will cheerfully pull this feature you rely on at the drop of a dime.
And it's not as if it doesn't make sense to pull this feature in the days of hot-plug; when your usb and firewire devices (which are all distressingly hotplug) are physically removed from the system, the teeny detail that you're still scribbling on the device (or, for that matter, that the device was your root filesystem) ceases to be important.
Personally, I'd think that given the history of Unix (see two paragraphs up, under "10 commandments of Unix") that the immediate response to a proposal of "we can just do a remove-single-device request on the root filesystem because it doesn't seem to remove the device on our test system" would involve screaming and trying to get to the other side of a distant ridgeline before the reactor goes critical.