Those rockets DO do a decent amount of damage to buildings.

H3ll, I was able on City to fly an Apache right behind the refinery, C4ed it to make sure whoever stole it had a nice fall, and took out GDI's refinery.

The kicker was that a Havoc stole my chopper, flew to altitude, the C4 detonated, he fell and died only to yell "WTF HACK WAS THAT? I DIED IN ONE SHOT!"

Tip: ALWAYS BOOBY TRAP CHOPPERS IF YOU KNOW YOU CAN'T GET OUT OF A BASE IN THEM. ONE C4 WILL TAKE DOWN A FULLY POWERED CHOPPER, so even if the prick gets it repaired, he doesn't get it, and you chance taking out the guy repairing, too.