well there surely is use for the regions, PAL60 doesn't replace NTSC if the NTSC version does not support it. And some NTSC games just don't support it like , Kakuto Chojin, Soul Calibur 2 (jap) and
some emulators do have issues too.
What are those issues? well there's a quick answer for that, it will run slower, instead of 60FPS it
slows down to 50, leaving the game in a constant slow-motion compared to the original state.
You loose 1/6th of the speed, some Games do even enforce that it has to run in 60FPS (LOTR-TT)
which makes it seem to load awfully slow on a PAL machine, yet it is only the video region. Sure
Pal60 is really nice, constant colors, nice resolutions, but some games do require NTSC, so if your
TV does support NTSC, i would most likely make it switch to NTSC due to the bad result that could
happen, and of course that i was meant to be played like that. (colors might actually look pretty
"washed out" in some games)
Now there is an other benefit in this, what if you left your xbox there, and one of your buddies or kids tried the videomode switch, and he sets it to PAL, that wouldn't be a problem, if you were in europe
but if you are in america, it can end up quite bad with a distorted display that you couldn't even read
anymore what you run. Now this could hotfix it simply for you, by pressing the button combination.
The same is for pal Systems being set to NTSC and the TV not supporting it, which will only result in
black & white, which is still recoverable.
The usability of this feature is indeed necessary for people playing NTSC and PAL games, wheter you are in Europe/PAL and don't want the slowdowns cause no PAL60 is supported, or in USA if you want
to either fix your xbox or if your TV supports it to play it in the 50Hz Mode it should have decreasing speed of the game, yet increasing quality. I hope this clears up that wheter or not you use this feature is still your own choice, you can disable it and it all works like before.