MS also keeps winning because they have billions of dollars to pour into the UX of their Office suite. The FOSS community doesn't spend a lot of money on hiring professional UI designers, and it's "do-ocracy" doesn't handle UI design well because UI design isn't seen as "doing" so much as nitpicking the choices of the programmers who are "doing all the work".

MS bribery is a factor, but if we use it as an excuse to ignore our own faults as a community then we're just screwing ourselves over.