It’s impossible for anyone other than us to tell tbh. Is it making money for one. How much lower is the baggage and retail spend on a short route ? And by stuffing gaps in your schedule with short flights, what impact does that have on punctuality and reliability on the long flights and so what EU261 would you have across the network?
All I can see is that jet2 have removed almost all such activity from their network with only a very few little bits remaining. My guess is reliability is a reason why they did so, but they’ve reached that conclusion.