I think that 'experimental' and 'avant garde' are conflated too much, which is where the confusion ive seen online asking why this isnt a weirder movie comes from.
I think that the big experiment of this movie is trying to find the limits of Lynch's style and what kind of story it can tell. The majority of the movie is quite striaghforward, but where the David Lynch-isims come in is where limits of the experiment is.
It was a good movie.