The lights are on
I can't speak for anyone else but I can speak for myself; I don't play the PSP "anymore" for two major reasons...
Number One: No support. The PSP's collection of games wasn't small by any means but there weren't many stand-out titles. I feel like a majority were either remakes of older games or sequels to games released on other platforms. That said, I was able to find some hidden gems but those alone weren't enough to keep me playing.
Number Two: The Vita is out. If you are confused as to why that would make any difference, think of the Vita as the Gameboy Color and the PSP as the original Gameboy. The original made way for the Color because the Color had new features which developers could use to make better games. Now apply the same logic to the PSP and the Vita. I, as a consumer, have no reason to play the PSP when there are better games being made elsewhere.
I hope you found this helpful and adds insight to your quandary!