Thanks for the feedback, we've seen this request come up a few times in the past and have added a +1 against it.
What you're currently doing by using Incidents as a means of communicating back to the customer is one of the workarounds we do suggest.
Here's something else you could try in the meantime. If you have a close relationship with the customer you could potentially create them as a User allowing them to follow all their incidents, problems, changes and releases in their service (if you have your account in such a way that allows them to follow everything within a service). Alternatively you could create them as a Restricted User (see attached screenshot of the permissions when creating a new user), which will allow them to only see Incidents, Problems, Changes and Releases on their watchlist.