Thats not at all how film making and special effects work. That would NOT be easier. That would all be much much more difficult and expensive than rotoscoping out a green sock over a leg. And more important it would compromise the art and that’s more important than any “representation” What does it say if you have to compromise artistic integrity to accommodate an actor that is literally not physically qualified to fulfill the requirements of a role. There are all kinds of jobs that have physical requirements and if you can’t meet those requirements you can’t do the job. A blown special effects budget was never going to turn Christopher Reeves back into Superman, nor should it.