My guess is that companies are trying to balance two things: Familiarity and Safety. Say you buy the next generation console you wanted, and the controller was the most strange and alien thing you had ever seen. It would make the console less approachable and they would lose money. As for cost, well, why fix what isn't broken (the overall controller design, not its functionality, those are two totally different things). If there are no major complaints about a controller, then they won't stray far from it (usually). If there were to try to create a revolutionary new controller that has the best ergonomics to date, and can be used by all types of people, they would have to pay a fair amount for that attempt and there would be no guarantee that it would turn out successful.