Why is Grand Isle so unbelievably hated?

I avoided this one for a long time due to the brutal rotten tomatoes score. I gotta be honest -- I actually really liked it. As always, Nic's performance was great. I really enjoyed the whole cast though. I've never heard of any of the other actors, apart from Kelsey Grammar, but every cast member here was super talented. Yeah I can see the complaints about Nic and Kelsey's southern accents, but this seems like an insignificant thing to get hung up on in an otherwise brilliant performance. The atmosphere of the film was constantly dark and uncomfortable, in the best way. The hurricane, the tense dynamic between Walter and Fancy, the mysterious dark secrets looming. So A+ on atmosphere. Now, granted, the ending was kinda sloppy. But it offered enough of an explanation to satisfy me, especially with how much I enjoyed the bulk of the movie. I could see this movie receiving a lower score than most of Cage's work, but 9% feels incredibly unfair.