I don't understand what's so difficult. Ever since the iPhone launched 6 years ago, you've always had to swipe to the right to unlock it. It's also been this way with the iPod touch and iPad. Even if Apple did some huge redesign, bigger than iOS 7, and I had never seen it before and there were two small arrows at the top and bottom of the screen, the first thing I would try would be to slide to the right to unlock it because that's what I'm used to. Plus, the slide to unlock text is animated telling you to swipe to the right. Even if you've never had or used an iPhone, it's highly likely you've seen/heard about it's lock screen.
Yeah I agree. Ever since the ipad came out, Apple always advertise that people already know how to use this tablet with the iphone. All iphone user should be familiar with ipad.
And now iOS is six years old, its a bit of dilemma I think.
By making it familiar with the user base who have used it before or move to a more advance state where we assume that people would know what "slide to unlock" means. And many basic gestures like swipe from right to left to delete or pull down to refresh (even though its twitter who introduce this)
But I think Apple has done the right thing. To move forward one step at a time. Slide to unlock without arrow in ios 7 is one example I think.