Empty hulls with just the basics ARE good for at least two things:
1) Put them in fleets, and train lots of fleets cheaply. Add real ships to the fleet as you build them, and send 'em off with full experience instantly.
2) Decoys. It never hurts to distract your enemy with a stack of 30 Whoopass-class empty-hull dreadnaughts while your real forces are elsewhere
