I do believe, that it is first not a question of money (being cheaper).

You do not have images of flag covered coffins returning home. You have no insubordination. You have the possibility to do economic promotion without being labeled as doing such (regarding international treaties (at least here in the EU)). You do not need all these training facilities.

Just to name a few.

So they will even do it, if it is not cheaper to do (imho). And logistics can be automated as well (delivery by drones, something like fueling done by other drones, and so on).

I believe we will see drone-carriers analog to aircraft-carriers being at least semi autonomous as well within our lifetime.