The amount of iron is pretty fine in deepstale iron ore deposits and on +height coordinates is allright for the start of the game but not enough for the middle or end of the game stage the today stage of iron farming is basicaly on farms in big amount but if you dont need the quadrilions of iron and randomly need a quick stack ot two of iron you can just mine in deep caves to find big iron deposits.
But the copper is very different story its sometimes really too much of copper especially on the start of the game when you mine not really deep and even randomly you can get some stacks of copper. Beacuse copper dont have an actual minecraft use for the amounts you can get this from ores sometimes you just dont mine this or just have some double chest of copper in your storage
copper only useful for the builders because its oly more a building block
more changes needs to make for a copper made the ores more rarer on the top not like the every cave from top of the world have a couple stacks of copper or just make a drop from copper ore like from iron ore not a 3-5 pieces from one ore without fortune