HB,
Evalu8ter is, as usual, bang on the money. There is a close link between USN catapult designs and USN aircraft, and longer cats would not deliver much improvement, as aircraft end speed is as good as it already can be.
Another factor is ship design - the CVN flight deck is essentially sized by the requirement to get 4 catapults installed. Longer cats would mean a new flight deck, and a longer ship, which would need more power, so an extra reactor.....
Launching off the cat at low fuel straight to a tanker usually happens when the aircraft design has gone wrong - the Buccaneer S1 was so badly underpowered it could only launch at low weights, with low fuel. Or it can happen if an exceptionally heavy weapon load is carried - a very rare event.
Hope this helps
Best regards as ever to those going off the cat
Engines