Why can’t you change caps/non-caps by pasting and altering?
I don't know what you mean by "pasting and altering." I have not seen any "convert to lower case" utilities, but I'm sure they exist, since they would be trivial to write. Such utilities would fix a problem that never should have existed. If the standard key sequence to start caps lock had always been, for example, Control-Alt-Shift, capitalization accidents would be rare.
There are utilities that in effect shut off the caps lock key, so you have to physically hold down the shift key to get the same effect as caps lock. AFAIK that's as good as it gets, short of removing the damn key physically.