Cost, both initial and maintenance. Though I'd hope the French Navy avoids "fitted for, but not with, 3 catapults" like the incoming nuke it is.If the third 'cat' is possible, why not?
That's running into manning issues more than buying the extra steel to make a 100kton ship instead of a 75kton ship. A Coral Sea-sized angled flight deck really only has space for 3x catapults, there's not enough beam to allow an inboard waist cat to clear the landing pattern. But there is space for 2 cats in the bow and 1 at the waist, and for all 3 of those cats to clear the landing pattern.However I'd say it's more about what the French Navy can "afford" rather than "want". I'm sure they'd love to have 4 catapults on a Gerald Ford sized carrier but without negatively impacting the rest of the fleet.
Back in December 2024, an order by the French procurement agency (DGA) has been placed for the development continuation of the A3B ammunition as well as for the procurement of additional RAPIDFire turrets. Regarding the Navy, eight systems will equip the BRF with two on each vessel. The seven future OPVs (known as PH in French) should also receive one each just as the future five future mine countermeasure vessels (BDGM program). Finally, the question remain open to equip the future aircraft carrier with such guns. Some PA-NG models showcased by Naval Group were showing four RAPIDFire systems fitted but the latter were not the final design.