I blame the consumers mostly. The N900 had the same graphics chip as the iPhone at the time, but that didn't stop my cousin from turning around to me and saying "uh, why did you buy that ugly phone?"

I actually met David Potter of Symbian fame once (he was the Chair of a research hospital in London), and asked him what happened to Symbian, who were the Nokia predecessor/successor/around at the time.

I can't quite remember his answer but it was something to do with different factions within Symbian unwilling to change for the future when it was clear that their best devs had already left for greener pastures.

So I think that time period, in general, had a lot of shifting moods both at the dev level and within consumer patterns, that led to the ultimate downfall of maemo