Don't forget niche users like yours truly who will use LCY because of the amazing views! Admittedly on both times I have done so, I have tied it in with events in London, but would certainly consider using it again, especially if travelling with someone from the London area.
My only problem with Scot Airways is that their one-way fares were about 3x those of Easy, but I'm sure they know their market.
It will be interesting to see how the LON to MAN market in general changes in September when the new Virgin timetable is introduced. I would expect the train to pick up some of these pax, and maybe for VLM to look at routes such as LPL to EDI or GLA, where the train is not so good. Also, discussing with someone from Sheffield earlier today - if LPL and MAN can support LCY services, why not SZE? Midland Mainline is lousy, with no line or rolling stock upgrades on the cards.
Sorry, should have added that I am based in Coventry, but journey in question was Coventry - London (event) - Glasgow & back. I would usually take the train from Coventry or fly from BHX to reach Scotland (once had to suffer diversion to EMA - hopefully never again).