I'd guess a lack of piracy, the PSP and Dreamcast both got destroyed by piracy, so third parties were less inclined to develop for them, and instead develop for their competitors

So you think that if PSP didn't have a piracy problem, the generation would have turned out very differently?

Well there are two possibilities:

1. Without piracy PSP would sell half the number of machines it did and DS would get another 20-30 milion sales from developing countries

2. Without piracy western developers wouldn't abondom PSP and with tons of good games it would sell better than it did.

Generally piracy is like a troyan horse which allows you to enter into market that wouldn't care if it didn't esisted.

Best example Poland - PS1 and PS2 were massively popular due to easy of piracy which translated into good PS3 sales when that userbase grown up , went to work and had disposable income.