Every airforce has it's specific requirements, JF-17 was made keeping Pakistan's requirements in mind..........It is a cost effective, single engine,all weather,day and night,multi-role aircraft..........
Made to be simple to maintain and upgrade so that should the need arise, Pakistan can pit as many aircraft against India. If they sustain damage, they land are repaired and sent right back up. When you have a multi-role aircraft, you can never be short of Bombers, Interceptors, Air-superiority fighters, cuz they are all in one.
Now, China has other needs, they mostly use Dedicated role aircrafts with greater range, more powerful engines......................so JF-17 doesn't cut it for them, they may induct a squadron or two..............but it won't become their workhorse like ours(i.e250-300 aircrafts).........