It would help Sony to get more people buying the Vita at the current price, however, placing the Vita at a lower price would get more people to buy it and then they would turn around and buy games/memory cards (which should also see a price reduction or at least give the new buyers a go at PlayStation Plus (cloud storage).
But there needs to be a bundle with an easy to access game (LittleBigPlanet PS Vita or PlayStation All-Stars) that remains bundled, with a price drop. With PS+ people wouldn't need a memory card unless they intended on downloading games. In which case generates more money for Sony.
But again it would need a massive advertising campaign to reinvigorate the masses to buy the product. Simply having a price cut with no marketing won't do much.