If the plastic ones are magpul mbus they are stronger than metal ones as in they will take more abuse and keep functioning. Plenty of drop tests show that the magpul plastic sights are tougher than the metal ones one most cases.
"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." — L. Neil Smith
The problem with being stupid is you cannot simply decide to stop doing dumb things...
"I crapped my pants to avoid the draft!!" -Ted Nugent