I like Ghibli but I'm not blind to valid criticism. It seems, however, that your argument is
>not every single character / scene serves to advance the plot
Mate, are you actually retarded? Not everything in a movie needs to have a deeper meaning. Some characters and scenes exist only to enrich the world and make it feel more alive.
It's even Miyazakis stated goal to break away from the norm and focus more on the mundane and the beautiful.