Certainly in a Windows environment joining a domain is a bit long winded... specify the domain, then an admin username/password, then a reboot. It would be nice to be able to dynamically join a domain - especially for BYOD type of environments, but also not to 'take over' the device as such. For example you cannot belong to a domain and a workgroup at the same time - so it may/may not affect your set up at home for example.

I think domain profiles are sort of the future, just as you can have many different wireless profiles which your device automatically joins once it has the critical bit of info it requires.