Viewers want movies to be spectacles. If we're watching something in a theater, we have high expectations of the production value. Otherwise, why even waste the time and money going to a theater? We can watch the "good", low production value movies at home.
> Rogue One: A Star Wars Story… would be impossible to do without CGI.
It's a prequel to a movie that had exactly one computer generated element in it, which was a wireframe model that took so long to render that they couldn't re-render it when the final design changed.They _chose_ not to make it without CGI. It wouldn't have been impossible.
edit: I'll just leave this right here - http://www.imdb.com/title/tt0034928/
Well, no, it's a prequel to the 1997 version, not the 1977 version you describe.
Decades ago, Finding Dory would have been hand animated (though, even that had moved begun moving to computers in the late 80s). I haven't seen Captain America, but I would guess similar types of movies existed before hand (the 80s and early 90s are full of over the top action movies and practical effects; some of which still hold up today).
Visual story telling doesn't require CGI. It might be the most pragmatic way to do things now (due to time, cost, complexity, etc.), but it's not the _only_ way.