Discarding an address? Nope.
And I thought I was the only one who's kept everything since day 1 in Bitcoin. In addition to what you said, keeping all your private keys, seed phrases etc., is important because you might need to sign a message from one of them someday. I know, it sounds very improbable, but not impossible. Somewhere, at some corner of the Internet, you might have posted an address that is found years later. Someone might try to impersonate you, after 10 years or even more. Signing a message from such address can be lifesaving; completely paranoid, I know, but there's a non-zero chance. We live in a world where the Internet is about 30 years old. Who knows what historians of the 22nd century will look up and which purpose they will have in their Internet.
And ultimately, it costs practically nothing to store a wallet. Even if you don't bear in mind the above, you gain absolutely nothing by freeing up the space a wallet takes (in both physical and digital formats).
