I think an answer to your question is that you could create new devices in the switches file that the too palette refers to and then when you go to the insert switch tool the new devices will be shown. I have done this with many of my custom objects and it isn't too difficult once you figure out how it is done.
But to stay on the point of wishes, I would like for the definition of a device to contain an attribute, like the old Softdesk way of showing switches. You could modify the attribute of the switch and change the "3" to an "a" or whatever you wanted to use. It seems it would be easier, much so, to modify a custom switch or annotated device this way rather than have to create a custom device all the time.