Developers used to just simply charge for software. You would write a program that others considered valuable and they would pay for a license to use it. Developers also used to charge for updates. Those same people who bought the original product would pay periodically when you added significant features and improved the product’s operation.
Software sales are not so simple anymore. There is a definite a downward pressure on app prices; many users even expect them to be free. Of course, “There is no such thing as a free lunch” (TANSTAAFL) so somebody, somewhere, is going to have to pay at sometime. If not, app development will not be economically feasible and apps will be abandoned. However, perhaps we should at least consider that a large part of the industry is moving away from the pay-full-price-up-front model.