Is there any positive hit modifiers for marines?
Chaplains Recitation of Focus gives you +1 to hit.
Incursors are a situational unit, that's good agains units that utilise hit modifiers and cover. I wouldn't want to bring them in a general list. On the other hand Infiltrators are more expensive, but they hae a 12" deny bubble. And it's not only GSC or orks. There are plenty armies that can and want to deep strike near you. Daemon bombs, Gate of infinity, On Wings of Fire, OBEL, Inceptors, Drop Pods, etc.
If you want to hold onto your doctrines, then you have to go full marine anyway, so no cheap screening units for you. In this case I would take a "phobos batallion". 3x5 infiltrators with comms, PhoCap and PhoLt. The infiltrators can protect your rear from unwelcome guests, screen out any deep strikers, counter act any enemy infiltrators, camp on objectives from turn 1, etc. They still get some re-rolls, which makes them more effective and the PhoCap and PhoLt can party in the back with your artilery/hellblasters/stalkercessors/eleminators. But even if you are not putting them in front, 3 units of them can cover your whole deployment zone, camp on rear objectives and deny the enemy last turn point grabs like LineBreaker with some re-deployment shenanigans or the last minute drop pod, people are planing on.
I'm not saying that Infiltrators are now a must include or the above is the best use of your points, but I see more tactical application in the infiltrators than in incursors. And yeah, the later unit looks silly too