Actually AFAIK there are at least some other backup systems for each forcefield and independent power sources, so you could probably blow away good chunks of the ship and it'll still coninue working. In the end run novel the Tarawa was bsically no more than a dead hull anymore with at least 1/4 of the ship completely destroyed and the forcefields continued working albeit blinking on and off for a few seconds...not that it mattered anyway since the flightdeck was on fire.
But hangardoors would be nice I imagine for the TBP guys at least and if anyone attempts to bring Wing Commander Prophecy ships to FSOpen, (I'm looking into your direction, Starman:p ) The Midays launch tubes had doors, and AFAIK the Tiger's Claw too.