I need to disclaim that I feel some frustration and disappointment with Ubuntu, too. I had hopes that it would become a dominant desktop OS, but it never did. It's not like there weren't major opportunities. For example that Vista fiasco. It's just that Ubuntu never filled any of the big vacuums. However, I mostly didn't care that much, so I never even investigated the details. I just observed the results.
I was replying to this. Ubuntu didn't become dominant simply because computer manufacturers didn't get around to use it. Many of them tend to have heavy ties to microsoft and in any case it will take decades if not millenia for both common users and manufacturers to change. And the destop linux community isn't too unhappy with being a niche os in general either. If they wanted total domination they'd just croudsource buy some desktop manufacturer and make it completely adopt linux and sell linux boxen at reduced price to make enough of a user base.
All science is either physics or stamp collecting. -- Ernest Rutherford