Easyjet have been very good at creating a market out of nothing. IOM might have a small catchment area but at LTN they have the UK’s second biggest catchment area of any UK airport. If the fare is right there are many people in the southeast who would venture there for short breaks.
Ryanair have been flying for years to places most people have never heard of so why not LTN – IOM for easyjet which is a place everyone has heard of.