...I own almost 150 games on the my Vita (including 30ish PS+ tittles and a few PS1/PSP games), and I only owned about 12-15 games for my GBA; people can
very easily get many, many games for their Vitas

.
As for Amplitude, it would fit perfectly on Vita; the games vivid colors popping off the OLED screen, being about to use touch controls, being able to play the game anywhere you go, the system being able to get DLC (its a Harmonix game; I would be shocked if there aren't downloadable songs for this), and the game being a good fit for the system. Considering it is a Sony platform and the fact it is coming to PS3/PS4, it might be a good idea for it to land on Vita (even if Harmonix gets someone else to develop the port).