LEDs last almost forever if they work within their parameters (mostly the temperature is important). They degrade quickly if they overheat. And above let's say 5W they will overheat if they are made out of plastic.

So - these plastic ones are designed to fail, so why put a proper electronics there? So they skimp on power regulator as well (and that's probably what killed your LEDs).

Buy LEDs with metal radiators - they are more expansive, but they aren't designed to fail in a few months and should really last decades.