One of the benefits is that it comes off very easily and doesn't require polluting paintstrippers to remove it
Therein lies the problem. How many edges are exposed to a 600 mph airflow... a hundred or so access panels, cut-outs around doors and cabin windows, gear doors etc. It could be like a snake shedding its skin.
Then you've got compound curves to contend with when applying a covering; that's not easy to do without leaving creases. And there are the complications of splicing in coloured cheat lines! If they're of various dimensions and shapes, imagine the stores logistics of stocking repair covering pieces for a Boeing 747 (which expose more edges to the airflow).