I don't have a Vita for several reasons:
- It is too expensive. Especially when adding the memory card costs and the lack of high quality titles (which would suggest a lower price).
- No Sony IP's interests me. If I tried out a few I would probably like some of them, but I don't wanna take such a great financial risk.
- Sales trends. At the moment they really don't suggest that support for the system will increase in the near future. Heck, as far as we know Sony might even drop support if the system bring nothing but losses.
- Lack of compelling third party titles. If there ever is a great third party title made for it, chances are they will or already have released a superior version of it on an HD console anyway.
- Controls are inferior to that of Xbox and PS controllers. Smaller sticks, smaller buttons positioned too closely to the right stick resulting in accidental button presses. (Or so I have heard.) No handles to give the user a good grip.
- The hardcore gaming experience is trimmed down significantly due to previously mentioned controls, worse sound (I don't like using earphones when gaming, but even then I don't own any high quality earphones), smaller screen (scaling down the epic feel of enjoying massive detailed on-screen objects and environments/landscapes).
While the last two points also applies to my 3DS, the 3DS compensates these issues with its unique software.
I think you have pretty much summed up the problems with the Vita, though I think it is as comfortable as possible considering portability.
I think sales trend is the biggest concern. Sony don't use their A teams on Vita and their B teams simply don't make as good games and if they are not willing to commit all their resources to it, then why would 3rd parties?