Deway Replacement Hand-Trigger Nozzle

The nozzle works well to start with but overtime the valve stem in the nozzle begins to warp and then becomes hard to operate as the nozzle begins to stick in the open position or will not open with handle. I wonder why the valve stem it made of a pliable plastic material and not metal like aluminum or some other cheat metal that would not bend when you actuate the handle. This is my second handle and the specs on it look the same as the other handle wich only lasted 2 months