two problems the vita has, first off its not being made for the kids and second the people they are marketing for dont want to carry a second device.
ok the people who play handhelds the most are generally kids, they carry thier 3ds or vita with them whenever they leave the house, the problem being Sony isnt marketing the vita for them at all.
adults dont carry handheld gaming systems with them to work and such, they would just use thier phone and play a few games here and there especially with the phones getting more powerful and bigger screens. Remote play is a nice feature but i have found 2 things i dont like any game that uses r3 and l3 and r2 and l2 you have to use that stupid touchpad, my hands are big and i always hit it by accident, secondly i dont need to play a game that badly in my house that i cant just turn my ps4 on, i guess i could always bring it to the crapper but most likely wont. They need to get the vita into the hands of kids if they want to sell more this requires them to market it towards them, hell i cant even remember the last time i saw a commercial for the vita....I love mine i play MLB the show on it mostly, and use it for Netflix alot especially when im cooking for my wife ill just pop netflix on and go to town on it.