Technically innovate at a rate which outpaces China is an assertion which seems quite unsupported by the evidence. Buying more F-15EXs is indicative of a stagnant culture which has lost the ability to innovate.
That seems like a misconception.
We are at the point of a cusp where an individual airframe performance is becoming less important that, perhaps, control of a fleet of active wingmen and programmes such as Skyborg aren’t getting the attention they deserve. A two seat F-15EX replacement for the F-15E with 4 Skyborg could vastly outmatch a J-20:or similar platforms.
In fact it may be the concentration on building more Gen 5 stealthy platforms by the Chinese and Russians which is wasting money on technological dinosaurs. Whilst Gen 6 swarms are the future…..
Remember the NGAD is seen as a family of systems, not an individual aircraft…