True, same goes for the piano... I hope the new Opeth includes much more "Per" in the mix. Let's not focus too much on "waah waah" Downer Dude with the "dread and darkness" comment, though, and not forget that it also can convey beauty, light and hope as well. I think it's safe to say that many acoustic stringed instruments just plainly allow humans to express emotion, period; especially the human voice.
The two times I've seen Opeth live I thought that the usage of the acoustic simulator sounded great. I can definitely understand why someone wouldn't want to use one in the studio. My guitarist has a simulator as well, along with two beautiful Martin acoustics, and there's just no replacing the acoustic guitars. Same goes for piano. Many of the keyboards out there do a GREAT job of replicating piano sounds, but nothing beats a real grand piano in the right room.