@OldLurker; Approaches 'clean' are not inconceivable, but large heavy airliners need to be slow to land - otherwise they may run out of runway in which to stop ! Flap-less landings can require double the 'normal' runway length to land.
Nor can you fly in clean, then stick full flap down at the last minute with just a mile to go, because it takes a while to slow down and settle the aircraft in its new config, so as not to destabilise it or the approach. It has to be configured in a controlled and gradual way.
Airliners increasingly don't use full flap for landing anyway these days, to save fuel.