You must be referring to the greater level of detail on the surface? This manufacturing is the most difficult part of fielding a stealthy plane. Sukhoi has not done this yet for the Su-57. It can't be done for those other fighters because it is probably quite a lot more expensive, time consuming, and requiring specific machinery, skills, and processes. Would PLAAF be happy with cutting J-10 and J-11 production rate by three or four times? No sometimes numbers are required to balance things and the optimal number of VLO is required.