What Gatwick Airport seem quick to forget is the connecting passengers that come off the BE domestic flights and into the BA and VS long haul leisure routes. Yes there is EZY on Inverness and Isle of Man, but no Interline possible and therefore your average travel agent in Inverness cannot (and likely will not) make a booking on LGW-MCO or whatever...either because they cannot see an INV connecting flight in their system or they know full well that there is an EZY service to LGW but will not recommended their clients use it as they'll earn zero commission and will instead book flights via MAN or AMS or something.
Sure, LGW isn't like LHR, AMS, CDG etc...no-one is pretending that it is. But it does still function as a hub (mostly for leisure traffic) in its own way and the Airport Authority doing their best to kill off small aircraft feeder services is also going to cause harm to (what's left of) their long-haul business.