[color=cc9900]Building something in a non-ideally shaped asteroid would be less conspicuous, as otherwise bored fighter pilots go "ooh look, a spherical asteroid" and fly over and blow it up.
I suppose Truespace kind of forces you to use booleans. In any proper modelling program, it would be easy to avoid...
I know it's not quite a box inside it, but whatever it is it's flat on the bottom. There is no point for that. Look at it - it's a load of rock. Build stuff in the rock, why would you want to geometrically hollow out an asteroid, cart all the rock away, then cart building materials back into the asteroid for frickin' towers? There is no point to it.[/color]