The USMC used the F4 alongside the USN as they always have. USMC aviators are trained as Naval aviators, deploy with USN ships, and support USN missions as part of the CVW. The ARG concept is different, and USMC STOVL fixed wing wasn't a thing in Vietnam. It's a more modern concept. You're projecting things that didn't exist into the past.
There are no compromises between the platforms for STOVL -- the JSF-B is a separate aircraft as it has been since the beginning and as you say in the sentence above. JSF-A and JSF-C are different airframes with different requirements and different capabilities.
So while the different variants have different wing surfaces there is no denying that the Air Force and Navy versions would've been designed differently if the airframe didn't have to fit a lift fan in it.
So then you're back to the fundamental question of why even bother. Parts commonality is 1/4th of what it was supposed to be. Costs are nowhere near what they were originally billed as, even with the most optimistic estimates.
Really the only virtue of the JSF approach was that it made the program too big to fail.
The size of the aircraft is driven by the need to carry large amounts of internal fuel and all internal stores, not the need for a lift fan for the B model. This allows all three models to operate with a reduced cross section for an expanded set of missions, which is the purpose of the aircraft.
Parts commonality is essentially non existent except for the engine and parts of the avionics -- that does make a difference and is a cost savings, but it's not the issue you make it out to be.
Costs are better than they were sold as, and their availability rates are better than they were sold as, and their accident rate is so low as to be non existent. It's a phenomenal aircraft and a capability that's going to completely change the balance of power in some regions of the world.