Despite the obvious advantages of STORL / STOVL ( if the kit allows ) the U.S. Marines don't seem to be driving the project along, hence the flat rather than ramped decks of their carriers - they put up with whatever they're given.
They'd get a ramp if they wanted one. The ski jump has disadvantages. For one thing, it gets in the way of rotary wing operations.
You've flown it ( or rather the prototype / simulators ) and I certainly won't; but when I say ' no vectored thrust ' I know that aft nozzle vectors a bit, but not as in the 98.5 degrees - all combined - like the Harrier.
For slower, heavier takeoffs and touchdowns, the aft nozzle needs to be able to vector upward to offset the nose down moment due to full[er] flaps.