Point is, PSP and the Vita were always marketed as the device for teens/adults which hurt them big way. The PSP back in the day had a really rough start but since smartphones weren't really a thing and the idea of having almost PS2 kind of graphic with the beloved Sony IPs + 3rd party support, was a huge selling point after a while. After the first exclusive GTA came out (which was also the good ol' game, for downgrading) and all the fuzz around piracy/homebrew and such, this thing sold like crazy for it's time. More units sold = more 3rd party support. If you take a look at the library nowadays on the PSP, you'll see many games which came from 3rd party studios, either exclusive for the PSP or games which came for PS2 and PSP. But the time it took, to get to that spot, was pretty long - which was fine, because the only competition was the Nintendo DS, which had a complete different demographic - no smartphones or other crap.
The PSP was also my personal entry point in the whole "scene" and I remember the huge steps pretty well. The first Iso Loader, ridiculous things like a modchip for downgrading, which you had to solder under a microscope (I still have one fat PSP, which has one, as a relict of the "old times"), the pandora battery, the D. Alex CFW ("hail to the king, baby"
) and so much more cool stuff.
Today the only reason the 3DS is going so well is because of the old nintendo fans and the demographic (which is primary childs and teens max - no adults), which still works for a mobile console. The Vita targeted adults - again- and those people simply use their Smartphone nowadays, if they want to play something. I mean, sure, the 3DS is selling great but even then I almost see no people plying it when I am in the city/train and so on. If I compare it to 2005/06/07, before the smartphone hype, it's a huuuuge difference. I saw people playing with their DS and PSP all the time - today, not so much.
Sony did almost everything they could. Sure, they could have marketed maybe better and more, but they tried with so many exclusives (which Foxy named a few of and almost all of them are fantastic), point is, they realised that "AAA-gaming on the go" for their targeted demographic, is simply outdated and they had to learn it the hard way. At some point you have to realize at a company, that you have to let go a product, if it doesn't work, even if it is a console and that is what sony did.
Japan has 3rd Party support sure, but outside of their usual dating sims, it's almost JRPGs only, so I wouldn't call that "full 3rd Party support". I love my both Vitas, I really do, and even if you have played all the exclusives, there is still no better JRPG machine than the vita (even better than the 3ds). I mean Tale of the Hearts R and both Hyperdemension titles were released over the last 2 or 3 months (3 great JRPGs in such a short period of time), with more titles coming soon + you can import some JRPGs, which get relesead in China first and have English texts then.
But if you don't like that genre and no Indie games, the deal is pretty much done. This will be Sonys last mobile device and I simply hope, we will find a native vita K-Exploit within the next few years, so we can have homebrew for that baby, since it is such a great and powerful machine.