...but the casual viewers would not be interested at one big CGI fest.
According to what evidence?
This is one of those bullshit beliefs that exist simply because everyone keeps saying
it. Until such a movie is actually made, it does
have a crappy story, and it does
bomb, then that's all that belief is: Utter bullshit.
(Hint: Most animation films have no
humans onscreen; it's all "CGI." Yet they rake in the cash left and right. Hell, I can't think of any aside from Roger Rabbit
and the Song of the South
have actual humans in it that were any good.)