"my kids have loads of GW stuff, 40K and LOTR mainly."
How chunky are the designs they have? Chunky lead holds up pretty well to abuse, but as soon as it gets thin it bends and breaks so much easier than plastic. Give your kids anything metal with a thin sword, rifle barrel, or bayonet and see what happens. Heaven forbid they get their hands on a lead/pewter spear. :)
And if they're just leaving their stuff around to be stepped on, ya need to teach 'em to respect all their toys. You never know when one of 'em will save your life. That tiny plastic sword you could poke an attacker with might not be there when you need it. And trust me, the plastic ones are way sharper than the metal ones. :)
"Both materials have their place and they are both vastly better than the bendy pre-paints. Talk about toys....."
And don't make me start on you. I should post the pics to prove you wrong.
Edit:
Here you go, and they're tougher than any metal. CMG Avenger away!