[delusional]

Attaching JIRA issues makes a ton of sense for features that are described in JIRA. If we're talking about a bug that was found by a developer, unmotivated by a ticket, it would generally make more sense to just describe the bug directly in the commit message. This is of course not true if the JIRA tickets are used for something else downstream, like informing users of fixed bugs, or tracking changes.

The other issue with tagging JIRA tickets is that junior developers will believe that to be enough (you can just read the ticket) and wont understand why they need to describe the change from a technical angle, when it's already described in JIRA.

[zb]

Commit messages are immutable. Linking them to a bug ticket gives you a mutable place to record any new information about the bug that you discover in the future. (For example, that it affected more cases than you originally thought, or that the fix caused another bug.) This new information will be discoverable when starting from the original commit (found e.g. by doing a blame on a particular line of source).

To fail to do so is a gigantic missed opportunity in my opinion. You never know when you will need it.