Not having any major franchises is far and away the biggest problem. The other factors would be minor issues if the Vita had a title at the level of Monster Hunter or Pokemon. Sony never created any major, unique franchises for the PSP that could carry over and now they're preoccupied with the PS4. In North America, having a kid-friendly IP is critical, yet they have nothing on that front.
They miscalculated, pure and simple. That, and the head start of the 3DS, which hurt a lot.
The Vita actually is getting a lot of quality games. The "it only has ports" line you some people parrot is ridiculous. They just aren't the games that pull consumers into the store en masse, as most of them are not established franchises.
Hopefully they'll get WWS working on a few Vita games after the PS4 takes off safely.
