they can be pretty helpful
i'm kind of biased since i fly a lot but i'm not gonna be like one of those idiot snipers that insist that they help by "locking down a point so nobody can cap it".
I myself roll rockets/radar/flares and strafe stuff. Usually vehicles and flags that are under attack/being attacked. Even though the rockets don't do much damage to infanty, making their surroundings explode can suppress them (it doesn't apply the "suppressed" effect, but it sends them running for cover), and if I catch some guys camping at the top of a 20 story building (like on karkand), there's nowhere for them to run. I only go after other jets if I'm being attacked by one or I can't see any ground targets.
I should probably go after helicopters more but the jet's cannon is so ineffective against them that I can't really do much. Due to the fact that the helicopter is usually moving, I'm moving really fast, and I have to fly directly at the helicopter to shoot it, there's a really small window of opportunity to actually land hits on them. And the hits I do land don't do much damage. I guess it's fair though, jets would brutally forget helicopters in the beta, and choppers have enough problems to deal with from ground units already.
tl;dr, ground attack pilots are bros, anti-air pilots are selfish