Not all of the Chinese stuff is junk. Some of it can be quite good. My Chinese-made Trucklite knockoffs have performed exemplary (lets face it, the original lights created a very low bar to surpass), at a very attractive price point. But at the same time, I still hang on to my old halogens, just in case something goes wrong.
As has been mentioned here before, the problem is consistency. The quality control for a lot of these products are sub-par, so two people can order the same product, but it may only perform well for one of them.
For the really cheap stuff, where the product can almost be considered disposable, or you have spares you can fall back on, it's one thing, but when you're protecting your windshield from a hood that has aspirations of flight, do you really want to take that wager?