yes but the visitors mainly arrive by car & train - I know this only too well as we visit friends in Cornwall on a regular basis and it can be HELL on both in summer. Holiday visitors don't need out & back daily flights - business does. But even if it has grown in terms in business & technology there are still no really large companies in Cornwall - just look at the numbers.
I'm sure Newquay can scrub along - after all Dundee is managing (just!) - but to see it developing any significant multiple flights per day to more than a couple of places is just dreaming. It's certainly got a better chance of surviving than Manston or Teeside