The problem is less so with trains and trams and more with bus routes. Over recent years bus routes to/from the airport have been cut back hugely.
A further problem with the lack of public transport uptake by passengers travelling to/from MAN is the lack of publicity (even with regards to the train). Many people that drive everywhere do not know about the rail connections to the airport. This also applies to bus routes, people nowadays don't know their local bus routes and therefore will travel everywhere in a car. This ultimately leads to the cancellation of certain bus routes.
The 200 bus service from Wilmslow to the Viewing Park is the next to go, ends on the 31st of March 2018.