Don't loose you mind over this
Tablets have no secondary input surface because they are supposed to be one surface devices. That's what tablet, pad is meant to be. The reason why mobile tablets are more successful than netbooks or tabletPCs with flip screen and pen before it is because majority of consumers wanted simple, one surface device. It's really that simple. Adding keyboard to market that didn't want to devices with keyboards for over a decade is like adding fifth wheel to car for stability.
OSX might be simpler than android or now windows, but you are missing the point. You can buy faster, better, more accomplished, more stylish, more powerful and much cheaper devices than ipad on the market EVERY SINGLE MONTH for years. And yet ipad keep outselling them all. Because tablet market is not about processing power, ports, connectivity, hackability or complicated apps. It's the same reason why iphone is so successful while better on paper Android and Windows phones don't get anywhere near the same market margin and never will.
I know Ipad is not for me. I could not, ever, just sit and browse, or just sit and watch video, without ability of doing something else on the screen in the same time. I recognise that and I never bought Ipad. But I am not a target audience. And most of you aren't either. You mum is. Your girlfriend is. Your lame biology teacher that can't find his way around all the icons in thunderbird is. And it's the trick that every manufacturer missed so far. Everyone between your five year old niece, through your jailbreaking shell coding buddies to your gramma can get familiar and become user of iphone or ipad out of the box in under 30 minutes. Design might be dated, but it works for just about every living generation. Meanwhile look at the new windows. Just look at it. From the squares everywhere, icons, colours to the messy layout - it's like mothercare board game from ninenties. I haven't even touched windows 8 phone or PC yet, I see those squares on the screen and I already don't want to. And I actually am, its target audience.
Despite the fact I really don't want IOS to dominate mobile market (because it is stagnated and single tasked, which is not acceptable in this day and age), I'm going to make a small prediction:
For all the wrong reasons and despite all of its advantages, this device will be a niche product. Windows 8 will be a niche product most will tolerate on their new machines rather than actively seek to upgrade to. Microsoft will not succeed in mobile platform, not in a true sense of the word, for many, many years. Because they don't understand it. Before first half of this decade is over Nokia will tip over and go down, purely because Microsoft doesn't understand what wide audience needs from portable net browsers and mobile devices. We'll meet in a years time and see what happens.