There was lot of pressure on Apple to licence their OS to third parties at one time also. Steve Jobs was big proponent of that notion that controlling both aspects of hardware and software leads to the best results.
I mean there is a reason why first party games whether they are made for xbox, playstation, nintendo or pc only are able to push the boundaries in terms of depth and quality.
Also porting some of their games to ios or other platforms will just devalue their software. Sure i'd like it as a consumer to just buy one hardware and play all games. From business point of view people in the industry who keep on proposing they go third party really don't know what they are talking about. They never present any numbers and just keep on saying things without any weight behind them.







