Earlier quoted context omitted.
> How come has it not been improved in years? Because it works. It's simply, "good enough.
Good enough is not enough.
Believe it or not, non-tech people do not want to learn the latest, greatest UI. They want it to work. Full stop. The shiny new attack surfaces....er,... features and the vicious circle of security breaches & updates may well extinguish the public's enthusiasm for "new". Ever see an average Iphone or Android user after a nightly upgrade? It isn't pretty when a user's functionality/productivity is torpedoed by a new design +/- features of new OS. As a tech savvy pro, however, YMMV.