My point wasn't that it's not useful, it's that missile costs don't scale linearly. If you're paying say 75% of the cost of a javalin sized guided missile, why not go for the bigger bang.
The main advantage of QN-202 would be its portability, where a single soldier can carry 6? Missiles.
Several reasons spring to mind:
- Number of rounds you can carry. How many more rounds of QN202 can you carry for every Javalin size and weighted missile? Making the QN202 bigger for more bang just reduces the number of shots you have, which is counterproductive if the original smaller missile was already sufficiently for the intended role.
- Ease of resupply. The PLA are doing a lot of work on using drones for logistics support, and the QN202 looks like it was designed with drone resupply in mind. Think of the massive benefits that would bring.
- Speaking of drones, the QN202 could also very easily be adapted for use on medium sized drones to give them hunter killer capabilities. Having a common round would massively ease logistics and reduce unit cost of rounds. The development might have even started as a dual track system for UAV and infantry use from the get go.
- Operating position. With a big missile like a Javalin, you need to shoot it outside or else you are going to take some serious backblast. Smaller missiles might allow you to shoot from inside buildings for better cover and survivability in the face of enemy UAC and FPV threats.
- Shooter signature: a big missile will be much more likely to be detected by the enemy, both in terms of direct attack against your missile team, but also in terms APS against the missile itself. With a small enough missile, it might be able to slip blow the trigger threshold for enemy APS defences.