This was discussed in some detail earlier on the thread.
The J-15, like the SU-33 is a big aircraft. It takes up every bit of space on the elevator.
The F/A-18F Super Hornet is also a large aircraft, but the US elevators are large enough to accommodate two of them. That's because those elevators also have to accommodate E-2D Hawkeyes, EA-6B Prowlers, and C-2 Greyhound aircraft which themselves are very large. Before that, they had to accommodate aircraft like the A-5 Vigilante, etc. So for a long time the US elevators have been quite a bit larger than most.
The Russians, when they move to the Mig-29K and take the SU-33s out of service will have quite a bit more room. Until the PLAN either designs their own cvarrier with their own elevators, or until they adopt a smaller aircraft, they will have to deal with the issue. And they are. The Russians have dealt with it for 25 years.
And the J-15 is worth it. It is a good fighter with a lot of capabilities.