Airports like Shoreham or Cranfield should be supported, but not necessarily by somebody like the OP with limited money trying to fly on a budget. And flying regularly from Cranfield I don't pay anything like they're charging down at Shoreham - it is very expensive real-estate.
People with, as you say, turboprops and piston twins probably do prefer a long hard runway. But equally, if you can afford to fly one of those, you can equally afford the fees at Shoreham, and most of us don't fly aeroplanes like that.
Incidentally, in half a dozen years I flew out of Popham I remember two propstrikes - a Yak taxiied into a signpost, and a Renegade over-braked and tipped on its nose. I think it's an overrated concern.
Grass runways can be very variable, particularly in the UK - Popham quite rightly bans circuits in the winter - on the other hand I still fly regularly from a much less intensively used grass strip close to Popham, where the only problems we ever have are when somebody forgot to mow it. But twins to regularly operate from good grass runways - White Waltham and Old Sarum come to mind.
GPS .v. NDB approaches. Interesting. A debate for another thread I suspect. NDBs are horrible, but they are the most common approaches published at UK airports - we should have GNSS approaches published and useable, and ideally certifiable portable GPS units for approaches. Unofficially of-course, we can all do that anyhow, but it becomes legally iffy.
G