I'm not too fussy when it comes to director's cuts. Though I still think the theatrical should also be preserved, so long as they've used original material I don't mind - in fact in a lot of instances I prefer. Manhunter is a good example. Unfortunately it's not available in its true theatrical version on DVD either (AFAIK).
It's all in the spirit of original material - to me. If I write a book, and I decide chapter 5 is not really needed and remove it, and release my book like that then that's the story. Later on I might say "well, the original chapter 5 was important to character development, I'd like to re-insert it". And in doing so I'd put a note at the beginning of the book and at the beginning of chapter 5 explaining this was not part of the book the first time it was published. And that would be okay, becaus people can still choose to read it how it originally was. However, if I was to instead write a NEW chapter 5, or re-write a lot of the other stuff in the book - then that's not okay. I'm making a new story to replace the old one.