Unity was supposed to be netbook interface, not a tablet one. Tablets (as we know them today, not tablet pc, which sucked) were not yet a thing then.
Gnome 3 decided not to be a clone of Unity, but not to be a clone of Windows 95. If you want a Windows 95 clone, you have a wide range of offers. If you do not want that, the choice was much worse. Gnome 3 improved that for those, who didn't want Windows 95 clone.
Incidentally, the only people who think Gnome 3 is terrible are those, who cannot let Windows 95 concepts go. Everything that is different, is going to be terrible, simply by the virtue of being different.
> Unity is a graphical shell for the GNOME desktop environment originally developed by Canonical Ltd. for its Ubuntu operating system. It debuted in 2010 in the netbook edition of Ubuntu 10.10.
> GNOME 3 was released in 2011.
That seems obvious. Because GNOME threw away GNOME 2, which people liked, and decided GNOME 3 would be a copy of Unity, which was supposed to be a tablet interface, and which distinguished itself only in being terrible?