A good article explaining the characteristics of CH4 UAV & advantages of its induction in PLA Army
link no longer works but I can see at least the following advantages:
1. it is a tested system overseas. so if there were design flaws or room for optimization, they would have been exposed through operations. especially considering China likely sent technical support along with the merchandise.
2. people say that these UAVs like CH4 is not suitable for high-intensity warfare, i tend to disagree. yes on its own the likes of CH4 cannot survive against a formidable air defense like Taiwan's. but in reality, it belonging to the army would mean that by the time it is to be employed, Taiwan's air defense would have been degraded to such state that it is likely only able to manage to defend some critical targets, and a low-value target like CH-4 is not likely enticing enough for it to engage. note that CH-4 can operate at over 5000m, so it can hardly be engaged with shoulder fired missiles.
3. there were already reports of the PLA using UAVs to guide its attack helicopters, so there is a niche where the CH-4 can fit right in.