Its probably earning them a lot more money for less R&D to add on 'newbie' friendly controllers to attract non gamers into buying consoles than it is to develop more powerful consoles and replace the entire system for the core gamer element only.
Thus we are stuck in a 'its fast enough, it looks pretty enough, it sounds good enough' era so why throw billions into developing a better one when they can sell an existing good enough one to more people?