Of all the things you can accuse Canonical of, Hubris is the least of their issues, if not the exact opposite.
Canonical believes, with some justification, that the GNU/Linux desktop cannot stand still, that what they've done so far is not good enough. Their problem is that they've taken this principle too far. In what feels like a blind panic they've taken the Mac UI and dumbed it down considerably.
Why the blind panic? Well, two reasons: first, tablets. That's something on the mind of every desktop OS developer at the moment.
The other: GNOME. Canonical wasn't going to be able to just merge in upstream updates from GNOME any more, with GNOME 3 everything was changing, from revamped APIs, to the GNOME 3 UI itself. The available options to Canonical were simply this: maintain, alone, an obsolete branch of GNOME, use GNOME 3 with the deeply unpopular UI updates, or attempt a hybrid approach and merge in the core of GNOME 3 but with a UI that Canonical would be able to maintain and that would suit the rest of Canonical's agenda.
In a sense, they've done the same thing as Microsoft. They've ignored the fact they had an excellent UI that nobody was complaining about seriously, believing what they have to be not good enough for the future. Microsoft didn't develop Metro because they thought they were awesome, they developed it because they thought they weren't. And Canonical's done the same thing.
And unlike Microsoft, third parties - the GNOME developers - were pushing Canonical into a corner and had the power to do so.
And, you know, I'm not going to be like every Slashdot whiner and condemn Canonical for this. They're far sighted. They're trying to push things forward. It's just, ultimately, Unity (and, in all seriousness, there are no other serious problems with current versions of Ubuntu, all of the complaints are about Unity) is just not quite what's needed.
The hope, I guess, is that GNOME Classic will finally give Canonical an out, something they can use to bring back the friendly, familiar, and powerful UI of Ubuntu past.