All this would do is either force the player to carry metals around with them (or always have enough free space to salvage them) - essentially a cargo space tax. Or induce the player into conducting micromanagement with floating cargo pods in order to repair damaged ships, while staying in one place to recover the items you dropped to make room for metals.
More complexity isn't always more good and some things are obfusicated for a reason. 'Realism' is not always a good thing to include in a game because it can get in the way of gameplay and turn things into chores.
If you're looking for something meaningful to do with metal, have a think about the player either reconditioning abandoned habitats etc, and/or building thier own.
This might need it's own thread...
More complexity isn't always a bad thing. Realism is not always a bad thing. In general, whenever the game gives us new ways to use commodities, I find that it's fun (using metal to build nav beacon, comm relay etc) or at least interesting (using volatiles for the neutron sniffer).
The point is, that you're CONSTANTLY finding metal after every. single. fight. There is no danger of not having enough. If you could use it to repair hull damage instead of losing additional supplies, that would be kind of a nice, eh? In fact, the fleet management aspect of starsector becomes more interesting and thought provoking the more resources you juggle. If the game is supposed to be about combat, just have it be the combat missions in the main menu.
I'd like it every commodity in the game had some kind of use besides just being a trade good. So far the ones that do are volatiles, rare metals, metal, supplies, fuel, crew, and heavy equipment. Did I miss any?