SRAAMs would always have its use case where it outperforms every other weapon in a jet’s arsenal, but whether that use case is realistic or likely to occur on the present-day battlefield is another matter altogether. If the J20 pilots think they’re pretty much dead weight that’s most likely from combat experience in large scale exercises like Red Sword, in which case it would be pretty well justified.
Also on a side note, in a vacuum having SRAAMs is always better than not having them (more options for a fight, less likely to be caught with your pants down and all that), but one has to consider the space and weight requirements of side weapon bays, and the weight of the missile themselves. Once you add these up, the comparison becomes a lot less clear-cut, and some very good arguments for not carrying SRAAMs in dedicate bays can be made. Especially considering how one of the areas of development for modern and future BVRAAMs is the ability to use them effectively in short range.
I think we'll get a clearer view of the answer the Chinese designers have come to when we get more details of the J-50/J-XDS.
I initially thought the J-20 would be the last Chinese fighter to have dedicated bays for SRAAMs, owing to its development starting back many years ago and as a counterpart to the F-22 with much the same combat doctrine, but the suspicious side bays of the J-50 have cast doubt on this.
A new thought I've had recently is that SRAAMs may no longer be primarily backup weapons for the Merge, but dedicated weapons to kill intervening "chaff" in contested environments (e.g., CCAs) where you need to preserve BVRAAMs to strike down multiple higher-priority targets (manned fighters, AWACs etc.). If the target is too fast for a gun, as the US has recently proved drones are with their failed attempt to gun one down, but not as evasive/protected as a fighter (that would require a long-range BVRAAM), then a truncated PL-10 may be sufficient. A small missile of such description may be able to fit into those small sidebays of the J-50.
The advent of unmanned close combat aircraft means the battlespace will get a
lot more crowded, even at high altitudes. Fighters that need to get in close will need to be able to deal with this. It may not be economically practical or even practically feasible to expend expensive PL-15s and PL-17s (which I imagine are carried internally in the J-36) on CCAs. The J-36 probably avoids this by using its massive radar to identify priority targets and snipe them from afar, but the J-50 probably goes with the "get in close and kill everything" methodology so it'll need ways to efficiently kill CCAs.