This is an easy thing to add but the biggest question on my suggestion is. Why? You might think "this is unnessesary" "autoshot plane" well yes it would be an autoshot plane to be honest but this could give more creativity to people like for example, making light bombers or make kamikaze fighters. And could bring more redstone capability for planes overall. There should be a small limit tho. Tnt doesnt do a lot of damage against movecrafts like tanks and ifv's so i think about 10-20 tnt minimum and also depending on size. (I will not expect this to be added if i am being honest but i would and other would love this feature. It can bring funny banzai! And kamikaze! Moments.)
I would thing it is best to add this for bomber category or it could make some CAS fighters with a weaker payload but could do damage to infantry.