Manchester has actively courted lo-cos for some time (Easyjet and Ryanair being prime examples) and this has generally been at the expense of its existing 'legacy' operators.
I don't quite agree with this statement.
About 10 years ago when lo-co was very much in its infancy, I attended a meeting at Manchester Airport addressed by the then MD Mr John Spooner. He very clearly explained the airport strategy at that time which was to encourage lo-cost airlines to operate from East Midlands whilst Manchester would concentrate on 'legacy' scheduled services and charter. At the time charter services accounted for 60%+ of passenger numbers. Also, the only lo-cost operator was Monarch Scheduled who at that time were a FULL SERVICE airline.
In the following years, the success of the lo-cost airlines at Liverpool, Leeds and to a lesser extent Blackpool, had a dramatic impact at Manchester in two ways. Firstly it hit the charter market extremely badly to the extent that charter today represents just over 30% of annual passengers. Secondly, the popularity of short city breaks hit the 'legacy' hard with many business passengers moving from the legacy carriers to the cheaper lo-cost carriers.
So the move by Manchester Airport in recent years towards more lo-cost services is in my opinion more a reaction to the reduction in charter services than anything else.