Swooping hawks a few things going for them.
Move and shoot 24"
Sure its a high powered flashlight, but a squad of 5 of them does get 10 shots with that flashlight. They can also keep backing up 12" and shooting it too. That really makes them hard to get into hand to hand, unless they really want to.
Move fast
Look at how much a jumppack marine costs. 25 points. When you consider that a jumppack costs 10 points, the cost of your swooping hawk is actually about 12 a model.
Free Ordanace Blast
So every time you drop 5 of them onto the board, you get a free ordanance blast. Its actually pretty handy vs IG and other light troops. See it rip away at the tyranids, orcs, and kroot too.
Ok in Hand to Hand
They are not super hand to hand monsters, but Ill deep strike them near a bunch of IG and then toss them into HTH with thier basic troopers. Ill also do the same when blasting Tau. Sure they are not great hand to hand fighters, but they are better than the tau and will keep them tied up.
Kick ass Exarch
The exarch really kicks ass. The web is skulls is just gross, and hes quite argueably the most powerful exarch you have.
In summary
Dont field them vs a 'hard' army. They suck vs marines, necrons, and chaos marines. As thats incorporates 40% of the total players, dont use them in legues where you are only allowed 1 army list vs many foes.