All of that are opinions rather than facts.

Edit: the bold part is true though, with the exception of Uncharted and maybe LBP.

People have heard of LittleBigPlanet and Uncharted.  Gravity Rush and Persona are action rpgs / rpgs and the last rpg that was a true system seller would be FF7 in my book.  Vita needs a system seller and they don't have one right now.

MR NintendoPie (I'm having trouble embeding my answers with this new text format):

What portable exclusive game could you produce, that it wouldn't be posible to better it in every concievable way for the larger format provided by HD. Bigger, more detailed Pokémons, incredibly rich landscapes in MH, super-realistic girls of AKB48 in all their barely-legal glory. You can do everything better in HD.

Controls and gameplay > graphics

Mr sethnintendo (I'm having trouble embeding my answers with this new text format):

A notion that the new WiiU will soon look to discredit, I fear?

Nintendo usually focuses on gameplay and controls first.  To have broken controls or boring gameplay can make any top graphics game dull.  I just don't think Sony knows how to market a hand held.  They marketed the Vita as console gaming on the go.  Doesn't look like that many people interested in hand held gaming want that experience.  Do they want good games with awesome graphics on the go?  Yes but they are probably more interested in the gameplay than graphics.   Take a game like Animal Crossing for instance.  Pretty much any game on the Vita outperforms it in the graphics department.  However, do AC fans really relish the most demanding graphics?  No.  They buy Animal Crossing because they like the gameplay.  Animal Crossing will outsell any Vita game and sell more systems than any game Sony could dream of putting on the Vita. 

Uncharted alone sold me for my Vita. The problem though is most uncharted fans think the Vita version is inferior. Even with LBP which is unquestionably best on Vita still does not have the interest of many sackboy fans.

Nintendo has a better reputation for handheld games so no one expects Luigi's mansion dark moon to be inferior to the original. This is Sony's problem with these big system selling ips.

I think it's a matter of social structure and collective mindset. The living room, in Japan, is a multi-purpose room, not an entertainment center, and bedrooms are, well, modestly sized. The infrastructure is not ideal for a big-ass 3D plasma, 5.1 surround sound reciever and reclining chair.

As for the way the japanese think, you want to fit in. Being different or even worst, contradictory, is not the polite way. So they game the way they would negociate any other affair that involves human interaction: follow the trend and try to enjoy it.

Not all Sony fans are gamers. Not all Sony fans like portable consoles.

The reason why I bring up Animal Crossing is because you are so focused on why would anyone choose hand held gaming over console gaming on a HDTV with surround sound.  Just look at its sales.

New Leaf has almost surpassed AC on GC sales with only being available in Japan.  Animal Crossing is the perfect series to counter your point of logic. 

You asked earlier "Who the hell is willing to invest hard-earned money in something as absurd and counter-productive as gaming on the go? If you have an HD console or high-end PC and a nice 55-inch plasma, where do you need to go in the first place? Do you crave the 5-inch gaming experience?"

Do these AC fans explain any of those questions?