I can understand selling hardbacks at a discount to get a big sale, which leads to big word of mouth, which leads to an even bigger paperback sale.
What I don't get is discounting that seems to devalue the very act of writing. If books are disposable throwaway items at £4 or under, or if hardbacks for less than a tenner, then we won't value them. Or read them. Or take them seriously.
I'm a writer rather than a publisher. That probably shows. But I still think most of the discounting that goes in is crazy.
That said, a lot of books that come out are entirely disposable and probably should never have been published.