You should Google up and see how common this problem really is. My example, I am a consultant. But I do have domain accounts in companies I consult. The OS that came with the machine (windows 7 home) had to be written over since it won't let me log in.
The point being, it's such an artificial restriction. Most PCs are laptops, and this really restricts mobility.
A remote desktop session into the my employer's network from guest wifi works fine within their building. My laptop running the rdp client is faster than the thin client they issued me with!
And where do you work that this is even allowed? Maybe it's only because I work for the Federal government, but there is not a snowball's chance in hell that I would be allowed to attach my personal machine to the non-guest network in any way.
BYOD (bring your own device) is the big noise in corporate IT, has been for a while. Now, it started with iPhones and macs and iPads, but if your staff have, for example, a Surface Pro 3 they like to use, you want some way for them to be able to use it in the corporate network environment, right?
Now, I'd question whether the right way to handle that is to join it to the Windows domain (I'd question whether having a Windows domain is the right way to handle ANYTHING in fact), but it's definitely a part of the corporate IT landscape nowadays, and MS should have some sort of a story for how you can do it.