Because for the foreseeable future, Apple's financial power and customer appeal gives it a powerful command over the industry--everything from component suppliers to programmers. That poses all kinds of problems, but it also means we'll be moving much faster into the future of computing--call it the post-post-PC era.
Yesterday's launch of the new iPad shows just how complete that power is. Sure, we'll still have Windows PCs, Android phones, and even MacBooks, but the iPad is on a steady trajectory that leads from entertaining toward essential.
The biggest effect I see from this direction is one for businesses. If you're thinking Windows machines are sufficient unto the day because Apple gears its products for consumers, you'd better think again.