The movie still holds up well for me. Others have answered most of your objections. The reason they look well fed is because when the movie was made, actors starving themselve, or gaining a lot of weight, or getting pumped-up for a role was still about a decade away. That kind of thing certainly wasn’t part of their craft for any of the stars of that picture. DeNiro and his generation of actors started doing it in the 80s. You might legitimately say, though, that their make-up should have made them look less healthy.
Yeah I would rather it be a readaptation of the novel than a remake of the film. Not that the film is bad. I like it. But there is much more meat in the novel that could be made into a film.
What I like about the movie is how it turns the cliche of the evil government on its head.
You watch the movie, and you think “the evil government is forcing us to eat PEEEPLE!” But that’s not true. The oceans are dead. There isn’t any more food. The planet is on the immediate verge of massive famine, probably within a year. Soylent Green is the only thing left. They know it’s only a stopgap. It can’t be sustained, because of losses in nutrients every time SG gets reprocessed. But it’s all they got. And they know the world is doomed.
Thorn getting the word out about The Secret isn’t going to do any good. Actually, it’ll just speed up panic and rioting and death.
Well at least the overpopulation problem will get solved.