You will not find a rage that is seeded deeper into the 'club player's' mind than allowing none squash activities on a squash court. And unfortunately many squash courts are being turned into gyms, creches and much more.
The obvious point that 'this is a big space and is ideal for other activities when it is not being used for squash', simply doesn't stack up, "it damages the floor!", "this is a squash court!" and "who lets them on OUR courts?!". These are common frustrations among squash players and understandably so in some circumstances.
However, some squash courts are purpose built for other activities such as those in Cheltenham Ladies College. These have 3 glass back courts in a line with 2 movable walls which creates a large space that is used for exams. There are bushings in the floor for plug sockets and the boards have a non-slip seal on them. So maybe in these scenarios it is understandable...
But what about smaller squash clubs? All clubs want to play on nice courts, so they need to look after them and the way to do this is to make sure the correct equipment is used to not damage walls and floors. But when a beginner walks through the door they are told they cannot play unless they have non-marking soles. This is especially prevalent in institutes such as universities where students want to play squash but are not willing or cannot afford to buy new shoes before deciding if they even like playing squash and want to continue.
Maybe the way is to relax our rules and regulations slightly to try and attract more members, or restrict classes, marking shoes and other activities to one court rather than campaigning against them. With a bit of luck this will offset the cost of having the court sanded a little more often not to mention increased popularity of our sport.
After all, don't we all want the 70s squash boom back?