Well. I don't love in NCL centre, nor do I visit BRS centre. My home is a 40 drive to the airport (A1 permitting). So 40 minutes, plus parking, plus parking fees, plus walk to terminal, then I need to arrive early if it's the morning flight as security is busy, minimum one hour, then fly, then arrive and travel to my place of work VERY close to BRS and the time saved flying is negligible. I also have the benefit of having my own car with and unlimited luggage allowance. Yes I can hire a car down there but booking, collecting and dropping it off is just more hassle.
The drive can be done in four hours door to door but I always budget for five to account for any traffic.
In the same way that people assume people revel city centre to city centre, which is wrong, it is also wrong to assume that everyone is travelling on a day trip.
All I am saying is that if the demand was there and the airline could support the route at a high frequency, profitably, then it would be done.
If EZY do chop the route then it may be tricky to find a replacement as BE have shut NCL. W through NCL will yield a business friendly timetable, or we can all remortgage and fly Eastern if they pick up the route.
The trains may be hourly but the last departure either north or South to get you to your destination in reasonable time leave quite early compared to the flight, so that may account for the hi demand on evenings.