That doesn't sound much different from "does the world need another hardware store?" or "does the world need another clothes store?". Essentially there may not be a need, but if someone wants to come up with an alternative bookstore, then they should not be prevented from doing so. In my view, I should be able to buy my e-books from whoever I want, for whatever reason.
Whatever the reason for a business to exist, as long its legal and legit then it should be allowed to do so.