At the moment it's not possible to get paper in the nether, so far as I'm aware, which makes a lot of enchanting harder. Diamonds can only be found in nether fortresses (And maybe piglin bastions?), which aren't too rare, but still make it really hard to get the stuff. Having another source for these resources would make nether survival more interesting. Now, as a general principle, if something is available in both the overworld and the nether, getting it in the nether should probably be harder and more dangerous, so don't make any of these sources too easy.