it is not GM's fault. It is the fault of the supplier of the heated windshield washer fluid module. They went belly up and basically just cut GM loose.
So really, theres nothing GM can do. They cant have the mfg fix it because they dont exist anymore, and they probably could not figure out an economical way to fix it properly without a redesigned module...which they cant produce without the windshield heater MFG, and they dont have the money to fix all of the modules because the MFG cut GM loose.
If losing your heated windshiled washer fluid is the biggest complaint you have about your truck I would say you are doing pretty damn well.