Oh, I dunno... it's easier to call 'em where the catcher's glove ends up. That way, you have fewer problems with the fans behind the backstop!
Seriously, I'm with you. By the time the catcher is moving her glove around, my judgment has already been made. I give just as much credence to the catcher moving her glove into the zone as to the catcher holding the glove still forever. That would be: none - except mild annoyance from time to time; it would seem I am most annoyed when I actually agree with the call the catcher wants... don't know why that is!