A long time ago I used to work in scematic capture and PCB design, knowing the process from start to finish may explain some of the problem, I'd say the issues could be much deeper, I.e component spec, system design, component quality and so on, thing with electronics is the design can vary hugely depending on who scetches out the system from the start, there can be many ways of achieving the same result, the designer could ignor individual component specs and push them beyond there specification, problem there would be inevitable failure, it may be a bleak post but I feel this could be the case with many of these cheaper electronic items from China. I think in many cases the designer/engineer knows what the flaws are but as you say R&D and QC are bypassed and these things make it to market regardless.
I maybe completely wrong haha