Jet 2 are a very cautious Yorkshire company, and probably know their market very well, and that market as yet is not long haul travel , to more exotic locations, which is probably how many of their customers would view the locations you mentioned currently.
That is not to say that they will not change, but I think they need more time developing their brand yet.
None of the above is hopefully viewed as patronising, but an honest attempt to look at their current market and where they MAYBE want to go.
Cheers
Mr Mac