This is a deficiency of Mastodon, not Nostr. It is necessary for supporting the legacy Mastodon network. When viewed through Nostr most people have usernames.
nostr:npub108pv4cg5ag52nq082kd5leu9ffrn2gdg6g4xdwatn73y36uzplmq9uyev6
Nostr isn't going to take off if only for the naming...I mean who the hell is "97cxyzab445..."?!? It tells you nothing...
nostr:npub1jlrs53pkdfjnts29kveljul2sm0actt6n8dxrrzqcersttvcuv3qdjynqn
Discussion
They look that way from poa.st too