Members of the device's development team told Japanese site Impress Watch, as translated by Andriasang, that Sony had decided to go with its own proprietary tech rather than standard SD cards partly because it wanted to "make sure they could have something with an equal condition for everyone."
They also stressed that the cards are an integral part of the system and not just additional memory, explaining that "they're 'storage' for the Vita and are used for patches, game data, download content and more."
On top of all that, "security" concerns were cited as another factor in the decision to insist Vita owners use Sony's own cards.
Elsewhere in the interview, the team offered a few more morsels of info on Sony's forthcoming handheld.
Although Adobe has announced that its winding development on its Mobile Flash Player, Sony is still in negotiations to ensure Vita Flash support.
Product Division Chief Hiromi Wakai promised that a PC utility that enables your computer to recognise the Vita as a mass storage device will be ready prior to launch, with a Mac version following in the "not-so-distant future".