@AC, "The coolest thing to do"
I can understand your point of view. Delivering the iPad concept very well is certainly what Apple is hoping to achieve (though my personal experience of their products' reliability is poor), and their commercial success thus far is certainly powerful confirmation of that.
"Not adding all those bells and whistles that frankly don't fit in the concept means more focus for making sure what it does it does better than everybody else. And that is what apple does best."
Indeed. But other companies can deliver that concept too, but they're likely to extend it to allow people to plug in USB devices, SD cards, etc as well. Apple's software superiority (I'll ignore it's apparent unreliability for now) is not something that Apple will be able to maintain forever. Microsoft and Google will one day (there's an 'if' there of course) match Apple's software completeness and user friendliness. When they do so but also offer additional things like USB Apple might have to think again about their concept.
I think that the moribund state of OSX on desktop / laptop Macs might be a sign of things to come. Having used both Win7 and OSX in various guises I subjectively think that Win7 is certainly on a par (and superior in certain apsects - taskbar in particular) with OSX. MS have caught up, and are cheaper. I know that Apple have been busy with their iSomethings, but really. Have Apple run out of ideas for OSX?
Microsoft may be this huge great slow moving beast, and Google's Android is laden with many severe problems, and Apple can currently run rings round the pair of them. But if and when Apple have run out of new ideas in the mobile areana too (are both Steve Jobs and Jon Ives on the way out?) it's likely / inevitable that others will catch up, and simply surpass Apple by adding USB, SD, etc.
Content, however, is another matter. iSomethings thrive on content. But what if that content is Facebook, or Flickr, or whatever and all those services and apps all become available on any half decent tablet (even an MS slab)? What exactly would Apple then be bringing to the party other than a cool looking slab that can't even read the SD card out of my camera?
Apple know this full well, hence their very restrictive model for deploying apps and music on to iSomethings which serves very nicely to make it hard for developers to support someone else's platform at the same time. Current market share + restrictive practises does serve to lock developers (and hence content) in to the iPlatform.
Their mistake, in my humble opinion, is to limit their current market share by cutting out those people who would quite like very simple and otherwise inconsequential things like an SD slot and maybe just maybe a USB interface. Even I might buy one then! Not doing so just leaves a hook for someone else to build a market share. But their commercial success thus far means that such user demand can not raise even a tiny blip on future-scope.