They already had a solution and they blew it up in the name of design.

That answer was the home button. More than just a simple feature, the home button acted as a safety net meaning it didn't matter how lost you got inside iOS, you could always find your way out with just a press.

The swipes and gestures might become secoind nature but they are not immediately obvious. It doesn't help Apple has no user manual or tutorial mode. Android isn't really much better but it does have the one-screen home buttons at least.