I can think of two downsides. First, there might be a better system of organization than “tags”, and if PG implements tags, then even if a better organization system is found later, PG will not want to spend even more time implementing this better system, so we would be stuck with an inferior system. Also, even if tags turn out to be the best system of organization, we would use up goodwill if we asked PG to make them for us, and he might decline to spend time upgrading HN in other useful ways later.
