... You know what the ribbon is? It's a patch. A patch to make bloated, difficult software seem easier to use. Microsoft has used the same GUI for so long it felt it had to come up with something else, and the ribbon shows that they're out of ideas. ...
I don't find the Ribbon to be a "bad idea" overall, it's just poorly executed and over-rated. If you take the excellent floating format palette idea from Office 2004 and stick it at the top of the window sideways, you basically got the same thing (a context sensitive tool palette). So you could argue that the ribbon came out of the work of the MBU, who are the only "Apple-guys" at Microsoft.
The problem is, you are right about it being a patch, but unlike any other patch, it's not optional.
You use the ribbon or you don't use Office at all. I think they were afraid that if folks had a choice they would not bother with the thing.
Another really bad (or good depending on your allegiance), thing about the Ribbon, is that by default it does not include some basic options (like "Save As.." for one), and is somewhere between minimally configurable and not configurable at all.
So it's not the UI idea of the Ribbon that's at fault, it's the
Fascist stupid way they implemented it, and all the heuristics behind those decisions. Like many Microsoft products, it's not designed to be useful to the end user so much as it's designed to promote Microsoft and their other products. This is of course similar to the way they are trying to tie Entourage into Windows Mobile devices (as if this is relevant for the average Mac user) and push that new file format down our throats.