Rock'n'roll began as teenage music, and all previous attempts to go "back to basics" partook of its original logic of adolescence, i.e. of desire, whether it was teenagers barred from sex and pleasure in the 1950s, working-class youth barred from career opportunities with punk, or radical youth barred from political representation with hardcore.
But twee goes back to an earlier phase, in which all needs are pretty much met, and the ones that aren't are yet to be conceived of. Not all the way back: it's not Rousseauistic naturalness that twee wants (though maybe noise does?). It's that magic time when one has begun the process of acculturation, but hasn't gone too far along. You know what you're supposed to want, but it hasn't yet got inside you. We see this best in the genre's management of gender roles: there are boys and there are girls, and they're dressed differently, but ultimately they don't seem all that distinct.