Simply put game development is not bug free. I have lost 17+ hours of game play because have getting soft locked in dialog cut scenes. A simple “exit game triggering a save” is not a solution to this problem with a title so buggy in this way. When you are in a soft lock state most commonly your input method is unresponsive while the client simply continues to run.
A ‘restricted’ manual save feature is used by so few games directly because of this downside and the added development cost incurred to fix a product ever time this system hits all the game game breaking bugs that invariably appear in today’s modern video games could be avoided.
It is a simple game design, cost saving, community appeasing choice, convenience vs angry consumer base.