Yossarian, you can destroy the runway "texture" but it doesn't effect planes taking off.
Just looks like dirt instead of blacktop.
Actually not being able to bomb runways is both a good and a bad thing.
On the plus side, there was no faster way to shut down an attack, rip up their runway and the attack died.
On the Minus side, it SUCKED trying to defend a field that constantly had bombs blowing chunks out of the runway. Even a 250 lb bomb blew a crater big enough to rip your gear off and all the attendant damage.
Plus you'd ussually swerve enough to not be able to get a good landing. Assuming you didn't blow up.
No, Runways not being able to get blown full of holes is one of the things AH got RIGHT in my opinion.