The benefits are you can employ people on cheap seasonal contracts and also free up UK based aircraft either to operate more flights, or you could use it to downsize UK bases. Watch closely, youll see his happen at another airline in the coming 2/3 years.
FAO/PMI/ALC/AGP/BCN bases would allow a significant reduction in UK based units or even bases. The lives of crews ruined, the pockets of the board lined with gold. But never cheaper prices for the consumer.
If J2hols wanted marginal locations they could buy seats on already operating flights. It'll be easier to fill 20/30 seats than an entire craft.