I think dust-jackets add a lot to the book, especially when the covers are either uninspired or intended to be simple-looking for bookshelves.

The dust-jacket for the Animal Man omnibus is way better than the cover graphic IMO, and the actual book covers for the Y - The Last Man HC's and the Watchmen omnibus are very bland. The dust-jacket also often provides review-quotes - perfect for introducing people to a new story. Yes, people shouldn't be judging a book by its cover, but we live in an age of low-attention spans, so those dust-jackets do help, lol.

I don't think I could ever complain about them. I don't think they significantly affect the final price, and people who don't want them can always throw them away, but for me they've become an integral and indispensable part of the product.