A huge problem with ticketing systems is then management uses it to track all productivity.

We had a ticketing system and one guy in our group had between 60% and 80% more tickets than the rest of us. So it would seem we were all slackers, however he took the tickets that took like 2 minutes to do (password resets, account unlocks, etc...), meanwhile i would get stuck troubleshooting a production performance issue that would consume hours. Management didn't care what the ticket was, they liked to see pretty numbers of tickets completed.

I might be the only one who had this experience, and i am not saying ticketing systems are bad, they are extremely useful, as long as everyone knows how they work.