To me, it wouldn't matter if Canonical / Ubuntu were using Unity if contributing to Unity didn't require assignment of copyright for your contributions to Canonical. If that weren't the case, then people could take the best of both worlds between Gnome-Shell and Unity and do whatever they wanted.
I don't even care if they're putting QT apps into Ubuntu. I don't care that it's not Gtk. Qt is open and free. Even Nokia doesn't require contributions to Qt to be given over to Nokia.
But the copyright assignment requirement effectively keeps Canonical out on their own island, and what you contribute to these Canonical-initiated projects could eventually be made proprietary. Caveat contributor.