Make Iron More Rare

(There's already one post similar to this, but it's from before the copper age dropped and I have a different suggestion for how to implement it.)

Iron pickaxes are the second-best type of pickaxe in the game in terms of how many blocks they "unlock"/are able to mine (since diamond and netherite ones work the same), and iron armour is the third strongest armour type. Despite this, currently you can get both of them in your first ~30 minutes of playing the game casually in roughly the same caves where you would also get copper from. This makes the addition of a copper tier much less meaningful on its own, since players can just skip it and go straight to iron, and from there slowly make their way to diamond as if copper didn't exist at all.

My suggestion is to simply make iron much rarer in heights close to the surface where copper also spawns, and maybe more common further down to compensate, instead of making any more changes to the copper tier itself. I do think this change would feel "weird" to older players who are already used to how easy iron is to find but I think it would be better overall for modern versions, where copper is supposed to come after stone tier and before iron. Iron is important for many blocks and mechanics, but ideally by the time you have enough to (for example) make an anvil out of it you should at least have a house to put it in and nametags to name/books to enchant your tools, not when you have just come out of your first big cave expedition.