It's really just comes down to software quality and treatment toward the system.
Sony treats the Vita as a place to send ports and spinoffs from series that usally place emphasis on presentation over gameplay. For example, Uncharted: Golden Abyss is not that enticing because it emphasizes presentation over deep gameplay mechanics, and other Uncharted games exist on more powerful hardware. The things this game does best are done better on PS3. Games like this hit a glass ceiling quickly.
And how many PSP & Vita games followed this same philosophy: AAA Console Game: Spinoff Subtitle? How many of these games were better than their console versions? How many of these games were not outsourced to different teams? And how many of those games are system defining games that people will still be talking about years later?
As for the games that don't follow that philosophy, how many truly notable games are there on the Vita? Not games to hold you over (you can get games like those on any system), but truly remarkable games. Games of similar quality to Link's Awakening and Tetris. Games people will be buying on a PSN store 20 years from now? If such a game doesn't exist, why hasn't Sony pooled together it's absolute best and made it happen yet?
Converse this with Nintendo's approach to software development.
- Pokemon's mainline entries are on portables. The selling point has never been the visuals, it's the monster selection, battling, ect...
- Mario Kart entries on portables are treated with the same love and care as the console versions and developed by the same team on consoles and portables.
- Super Mario 3D Land was developed by Nintendo EAD 2, who also developed Super Mario Galaxy 1&2.
Why do people care more about these games than AAA Console Game: Spinoff Subtitle? Software quality; it's the care and respect put into the product. It's the difference between "This is great
for a portable game," and "This is a great game." A subtle difference, but also a generation defining one.
So there you have it, if Sony wants to pull the Vita out of the handheld gaming ghetto it has to start with a 180 degree shift in software development philosophy.