It's already been clearly stated that Luton welcomes G/A, but it doesn't
need G/A.
They publish their prices for all the world to see, and if you don't have a pressing need to go there in particular, go somewhere cheaper like Cambridge or Duxford.
Agreed, many other airports in Europe don't charge half as much as some UK establishments, but who pays for the running costs of the airports - the local ratepayers.
With the very occassional exception, the state of the smaller airfields in the US is reflected in what they charge you - the lack of upkeep is noticable.
In the UK the vast majority of airports are Ltd companies which get no local or government subsidies, right or wrong that's the way it is, and they have to stand on their own 2 feet.
Even though the running costs are very high, the majority offer significantly reduced landing fees to accomodate G/A, and also offer en route services (such as radar/flight planning/met) free of charge.
I suspect that the very large majority of G/A users will never have the need to go to Heathrow or Gatwick - but will bitch about their right to do so and not pay a dime in the process, because it's their democratic right to air their views.