From a practical sense from someone who has lived with a well for the last quarter century, the pressure switch is the first place a person will go to try to fix this thing and that is the best place for the disconnect. Having one down in the well is impractical although I assume someone might want one at the well head. The problem is, unless you have a separate box for the disconnect and the wires feeding the well, it is a distinction without a difference since the line side of the disconnect might still be available to the repairer.
As an OT aside, I finally gave up on screwing with well pressure switches and I put mine on an Amp plug with a Hansen quick disconnect water connection. I keep a "hot spare" so when I am out there in my skivvies at 2 AM I can just swap it out.
I also built a "house" for my well equipment that keeps it out of the weather but I guess "freezing" keeps yours inside. In Florida carpenter ants are the biggest enemy of pump switches. It seems to be a perfect home for them
