To echo an earlier discussion in this thread, all creative rules can be broken but it takes understanding those rules in order to be able to break them. Sometimes you get something interesting, but usually you get post-modern slop that is wanked over for no reason beyond being 'different.'
Dune uses an omniscient narrator which has fallen out of style, yes, but Herbert doesn't misuse it from what I can recall. It's been way too long since my last read of it.
The issue with POV switching is when it leads to reader confusion or it is a lazy effort being done by the writer to convey details (reactions, thoughts, etc.) that could be shown rather than told.