+1I would have answered, "Because they're made out of metal". But that's just me.
I might be able to follow that argument if we were talking about saving a half pound but how much could we possibly be talking about here? 19 grams?+1
But some will argue that Plastic Composite is lighter depending on its application for any real benefit.
For bashing, Alloy metal is always better. And "clamping" Alloy hexes are probably best.
I switched to aluminum hexes on my 12mm car and it rounded out all the plastic hubs. In particular the ones that come with my Prolines. I have since moved back to plastic because it's way cheaper to replace a little hex than have to call it a day because I have to buy new wheel hubs (that cost $12 for four of them, and two are the wrong offset so are utterly useless) and swap it out.I've been using plastic hexes with 4s no problems yet.