Personally, I think the optimal ticket system would have this data for each ticket:

* A unique, prefixed ticket # (JIRA gets this right)

* An assignee (like an email To:)

* A reporter (like an email From:)

* A one-line summary (like an email Subject:)

* A multi-line body (like an email body, but ideally with markdown)

* Attachments (like email attachments)

* History for edits of all of these (not like email!)

That's it! It really is basically email, but with a unique ID, and editable with history instead of immutable with replies, and a decent UI, perhaps RSS + notifications.

Unfortunately, everybody else seems to think that their ticketing system should embody their vaguely defined and ever-changing workflow, prioritization, approval, and release management system, so they want to be able to add any number of possible statuses, approvals, workflows and and all the rest. Once you add that, you end up with another JIRA or ClearQuest or BugZilla, and the cycle repeats itself.