iPad Why do we need that?

iPad, released on about Jan 28th 2010, "a new most advanced product", "it is so thin and with big screen"... Although the video from Apple store implies how great iPad is, it is just a big iTouch. It is true that there are many advance technology has been build in iPad and I will be happy to have one if it is free. However, the "ability" of iPad has been limited into "iTouch". Why? If you think about the following questions, you may understand what do I mean. First, does it has a microphone? Many iPhone applications will not work on iPad if it doesn't have a microphone. Second, can it make phone calls? (You may use bluetooth earphone to listen and speak. ) Since they Apple has that many advance technology, why don't just build it as a computer in hand? When the iPad has been build into such a big size, like your full size text book(but much thinner), what it can do is still just browsing and like an iPod. The operating on iPad is still similar to iTouch. If iPad can run Mac OS X, if I can make note for my class or the meeting, if I ca use skype or make phone calls, then I will be happy to have one. GPS, SDK on iPad? May be Apple just didn't get the point. It make me feel that iTouch is a revolution, but iPad is not. I assume the stock price of Apple will drop.