May I as a passenger just ask something? Isn't it going to make it much more difficult for ATC if all aircraft look the same? Just imagine Heathrow with a row of aircraft all exactly the same*, the only distinguishing feature being the registration which may or may not be easily visible - how is the ATCO to tell if one happens to take a wrong turning, or instruct another to "Follow the XX" in poor visibility? Surely it would also predispose to accidents happening if the ATCOs are constantly having to check up on which callsign belongs to which aircraft each day? Surely a regular callsign is a safety factor rather than a risk? Can you imagine the situation where two aircraft manage to get themselves into a dangerous situation which needs immediate resolution and the controller has to try to remember the callsign of the day for both or worse, look them up?
I am aware that I know very little but these are just a few thoughts which occurred to me. Perhaps someone with much greater knowledge than myself would care to reassure me that this would be highly improbable :ok;
*I seem to remember hearing something about a problem with BA's tail artwork not being recognised by some other airlines and thereby causing confusion