The only disadvantage I see to cutting Mustafar is that you just start the film and there’s Palpatine, with no build up. Would prefer to see that finding him at least took some doing on Kylo’s part. Like I know that we can infer that it happened offscreen but I think it’s better to see that effort play out onscreen.
I’ve had the same thought… one of the big complaints that many people had was that Palpatine showed up too early. It’s really gonna be picking the lesser of two evils - Palpatine shows up right away and out of nowhere, or gratuitous, flashy music video fight scene that makes no sense