>>555402
First reason is Navy doesn't want to provide air support for them, it would cut into the total aircraft complement of even a supercarrier, and it's easier to make requests from marine command structure.
Second reason is fleets are usually more widely dispersed than people think, having a few harriers at hand is a good thing for a LHD.
Third reason is the fucking brits needed it, they actually pushed the most. Even adopting the harrier is just kind of a weird military aid to UK that lets them keep their pride and pretend they're helping.
>>555404
It's against the landing ops manual, but not inconceivable.
For example in great-power slugfest, the supers would be the first to get taken out. A Russian blue water ship would spam its whole AShM load at the carrier even if it's massive overkill, because it knows corvettes and coastal batteries can easily rape an amphib carrier if it comes into green water zone around Russia. If the worst happened - the marines would have to fly CAP.
Other relevant reasons outlined above.