i heard it was safer
i don't think so that it's more safer, try to launch X as normal user with a DM. it's more safer than launch it with root privilegies... A large part of DM doesn't accept this behaviour.
I agree with @ ray, just a convenient way to simplify the use of X servers whith a "beautiful box.
For me, this kind of applications bring more trouble than it's solve (maybe i'm wrong)