Good question, one I’ve had over the years. I think Asana would make a rather nice ITSM solution, except for one thing - for whatever reason, Asana refuses to include a Task numbering system (see Feature Request: Task Numbering). An ITSM implementation without automatic task numbering is just asking for pain, IMHO. There have been some groups that have creatively addressed this Asana shortcoming, but for me, this is something that needs to be inherent in the system. It’s too important, again, IMHO.