That's the problem, the Marines want to field their own superfluous air force. USN carriers routinely go to sea with understrength airwings, its not as if there's not enough room on CVNs to support Marine F-35Cs.
Eh, something like a F/A-18 has somewhat short range but the Super Hornet is better in that regard and there's always mid-air refueling. It simply doesn't make sense to jeopardize the success of the backbone of American airpower for a mission capability that is niche.
I mean, when has the Harrier ever been the difference between success and failure for a USMC operation? Sure it's nice, but it's also a jet that is very difficult to fly and prone to crashes.
The Super Hornet has something like a 350 mile radius with a "normal" strike package. That's not very much, and it gets worse every year as US carrier fleets are forced further into blue water to deal with the latest Moskit descendants.
That's why the Navy is so hot to develop the X-47 into something they can deploy.
If refueling aircraft are available then far more capable land-based aircraft should have been used anyway.
As far as when the Harrier has made the difference, well, we haven't fought many pitched battles lately, so it's hard to say. But you can't design a military with the idea you'll never have to fight a pitched battle.
EDIT: By the way, one of the advantages of the F-35B is supposed to be that its design is inherently less crash prone. We'll see.
> As far as when the Harrier has made the difference, well, we haven't fought many pitched battles lately, so it's hard to say. But you can't design a military with the idea you'll never have to fight a pitched battle.
That's the thing though, by shoehorning that VSTOL requirement into the program, we've made the F35A and F35C significantly worse aircraft. That in turn may mean that we may end up in a more difficult conflict because of the shortcomings of the aircraft.
Sure, if at all possible you want your military to be able to handle all scenarios. But truth is that the budget is not unlimited (as the USSR found out) so you have to distribute your eggs such that you get the best capabilities for the most likely scenarios.
I'm sure the F-35B will be less crash prone than the Harrier as well as more capable. I just don't think the costs justify it.
Marine squadrons routinely fly off CVNs with their F/A-18 Hornets. Institutionally, they have a long memory of not having carrier support in WW2, so they cling to this notion of operating their own air force.
For more details on exactly why the USMC is so afraid of being without carrier support, see accounts of the Battle of Guadalcanal. I recommend "Helmet For My Pillow" by Robert Leckie, which was also one of the books used as a basis for the HBO miniseries "The Pacific".
Naval aviation is of extremely limited utility as a result of a short range. If the fighting starts or moves inland the carrier is mostly useless.