J-10 has an adjustable intake which is essential for reaching its designed goal for speed. But it's heavy, complex, hence controversial from the early days (is the weight actually worth it?). Later when DSI is better studied and understood, it shows potential to be (almost) equally effective but a much lighter structure.
F-16 wasn't expected to be the best air superiority fighter to begin with, hence speed was neither a big requirement, nor a big problem (it has an excellent engine), so it chose a non-adjustable intake that is already very weight-efficient. DSI could potentially make it fly faster but that doesn't seem to have attracted a lot of interest (and investment).