Closed bugs are still easily searchable in just about any bugtracking system, whereas deleted code is much harder to dig up (you're less likely to even look for it, and if you do it's harder to find the relevant parts).

I agree that closing bugs you don't intend to act on soon is reasonable; I disagree that this makes it not worthwhile to have filed it.

FWIW I also agree that todos specifically about certain lines of code, i.e. todos that will become irrelevant if the code is rewritten at all, should be in code. The limit of that is probably roughly "TODO return the right error subclass". Even "TODO pass more information into this function" is probably past that limit, since it affects at least two spots in the code.

It should just follow a retention policy. If no action on it in the last 12 months just automatically close it.

Otherwise issue tracker has thousands of items that the team will never realistically work on.