Sadly, I think the answer is less physics and more chemistry--and not the good kind. The ice creams you are likely describing have been barraged with food stabilizers, emulsifiers, and other gelling agents which have nothing to do with sugar, eggs, and cream, and everything to do with getting texture out of "milk base" or whatever dreaded concoction frozen-yogurts, low-fat ice creams, and over-processed brands employ.
Make sure your ice cream has very few ingredients, lest you accidentally eat iced-emulsified-dairy base instead.
@Michael is right on, that faster, lower-temp freezing takes for smaller ice crystals which are creamier. Just make sure you know the difference. For interest, check out iCream which uses liquid nitrogen on the spot and claims very soft results do to the low, quick freeze.