But with the narrative being "this is the future", they were more or less pressured into it. The designers as well as programmers are volunteers and I would imagine designers want to work on the "cutting edge" even if that cutting edge is a complete disaster for users (just Microsoft's redesigned UI was).
What changed is that display and battery technology got better. I went from carrying around a tiny PC with an undersized keyboard (remember the Eee PC?) to one that weighs less, has a full size keyboard, and sports a display larger than the one the came with my first desktop computer. On this hardware, a traditional desktop environment feels cozy, while Gnome Shell feels foreign.
It works as a converged desktop too. Windows can't do that, OSX is only just getting there. It is impressive that an open source project is so ready for it, really.