Good story today in Discovery News about this topic that seems to be constantly asked. The answer is simple: People expect Apple to change their lives because they've done it many times before.
Sometimes you simply have to give credit where credit is due. Apple remade the computer, music, and phone business by making complex technology more accessible to more people. Yet sometimes pundits want that last "more" to be "all" - but Apple isn't aiming for everyone.
In much the same way that Henry Ford revolutionized the "getting from here to there" industry, the advent of his inexpensive 'horseless carraige' made transporation accessible to more people than just those who could afford to own and maintain a horse and buggy. Today's automobile industry provides something for everyone - from race cars to electric cars - yet no one company addressess all the needs of the market. Apple is trying to maintain its position as a premium brand while offering something for more people than ever before.
Remember that the same was true for computers, music players and tablets. Apple focuses on making it so much easier to use technology that people who never were in the market for a solution suddenly find themselves drawn in. In many ways Apple has democratized innovation and it is probably rewarding to them when others copy their designs and thereby reach many more users. Apple may have popularized the use of mice, icons, and windows but now everyone uses a computer because of it, and because of Windows, Linux and more.
Why do we think that Apple failed because they might never own 100% of the market? I think we should applaud the fact that Apple made the market and are content to own the slice where the money is. I hope that money is right now fueling creative minds at Apple to reinvent yet another industry. We're all waiting.