What intrigues me about the movie (and this is dangerous territory, as I'd hate to spoil myself on it), is that it seems that about half of the cast of the show was in it at one point, but their scenes got deleted.
I'm curious if perhaps a handful of them were just incidental cameos that Lynch felt were not necessary to the overall flow of the film?
The shooting script is out there and here is a great piece looking at all the missing scenes and dialogue.
Obviously serious spoilers for the series and film on this page. check it out though if interested once you finish.
I haven't read this through in awhile, but I remember a lot of the deleted character stuff was, as you said, mostly cameo type roles. A lot of the scenes were more lighthearted and Lynch likely thought it would have felt disjointed (the film is much darker than the show).