It would cost a lot of money (and time) to develop, but why do you feel that's necessary?
Pacific Theatre. The moment you're looking at controlling island chains, you're looking at a whole immense theatre full of islands of all sizes, where airpower(and the ability to deploy it at will) matters the most. In return, the most direct way of dealing with airpower is attacking its basing.
During the pacific war (which is unavoidably a go-to reference), both sides had to develop options to get this airpower to new locations, rapidly, freeing fleet carriers from those duties (and sparing them the vulnerability of being tied down).
For the Japanese in 1942, those were seaplanes and seaplane carriers(as well as the 4th carrier div, i.e. Ryujo, acting independently from the carrier force). For the US/UK(from 1944-43 onwards) - same seaplanes and seaplane carriers, but also massive adoption of escort carriers into amphibious support role (direct ancestors of modern LHA/LHDs, by the way).
Both were useful both directly(launching various air operations), but, perhaps even more crucially - in their ability to establish new bases&fly in the aircraft.
Seaplanes, smaller planes for smaller decks, or whatever is of secondary importance here - times change, technologies change. What's more important is that there is a complete niche for a line of combat/support aircraft with good austere/rough/short field performance.
For decades to come, a manned, fixed-wing jet wing is a
necessary component of airpower, hence - the need. Simply because AI won't replace humans for some time to come.
CATOBAR drones(thus, EMALS/traps question) have nothing to do with it -
both are needed. It isn't even a question of either EMALS drones or STOVL fighters - it's a necessity to have both lineups for this theater.
3/8 suitable decks are more of a topping of a cake - just to get full possible utility of them.