Re:
i'd guess the main reason they are built radial is that most people who buy Tune hubs want the lightest weight they can get, building radial saves a minimal amount of weight but every gram counts to some people and they will do it, so 2 cross will most likely be fine, personally i'd never build a set of wheels radially unless the rider was very light themselves. i had a radial wheel a few years ago that when giving the bike some stick would flex terribly, rebuilding it 3 cross sorted it out, this was on a road bike though, front wheel obvs.