The U.S. Navy plans, to equip future aircraft carriers with electromagnetic catapults, have been put on hold for a bit, while the software is perfected. The mechanical aspects of the electromagnetic catapult are pretty much solved, but the test model the navy is working with has been having some serious problems with the control software. The plan to put electromagnetic catapults into the next carrier (CVN 78, USS Ford) cannot be dropped, because the Ford is under construction, and a massive (and expensive) redesign would be needed to make room for the bulkier steam catapult. So the electromagnetic catapult will be made to work, or else (the navy will suffer an epic fail).
The electromagnetic catapult is preferred because it puts less stress on launched aircraft (it moves the aircraft forward more gradually), requires fewer people to operate, and is easier to maintain (not much plumbing, fewer mechanical parts and lots of sturdy electronics). The gentler treatment of launched aircraft now means that smaller aircraft can use the catapult.