"Never trust a man who has something to sell"
Thats not a slam at Jobs, thats a precaution to anyone who thinks your Honda dealer really believes the best car for you is a 2012 Odyssey.
The concept of "Gorilla Arm" is true, but it is a ridiculous reason to say that touchscreen doesn't belong on computers. Ask any teacher how their arm feels after doing 3 back to back sessions where they're writing on a chalkboard and they'll tell you their arm is sore. So why the heck haven't teacher unions had chalkboards banned from schools? Because sometimes the best methods aren't the most comfortable.
Touchscreen is not the best method of input for 100% of all interaction with your computer, but mixed with voice, keyboard/mouse it is an addition that will enhance the computer experience. So to believe that touchscreen will never hit vertical surfaces because "Jobs had a point when he was selling us a non-touchscreen product" is silly. Touch is the future and Apple will more likely lead the way rather than avoid it.
What if the man who is trying to sell you something says something that is true?
Does it make it automatically inversely not true because the man who said it was a salesman?
A trackpad is essentially a glass screen. Why touch the screen when you can just touch the trackpad and even gain quicker leverage over a larger area from a smaller one. For example if you wanted to click the top left corner, on a trackpad you flick your finger and the mouse is there via mouse acceleration, as opposed to moving/hovering your whole hand/arm all the way to the top corner. Its less efficient and a hassle.
Voice commands are a lot less commonly used than you might think by the masses. People don't want to have someone else hear them give commands, its awkwardly intrusive to both parties and is rarely ever useful compared to doing the mouse control version of it. People don't want to disturb their privacy bubble by saying things out loud. Even when you are alone its just awkward.
Maybe I will set a voice timer once in a while, or maybe use Siri while driving. But its so rare.
There is no reason to need a stylus on an iPad. You either use the touch keyboard to take notes, or a bluetooth keyboard. Either way its faster than handwriting. Handwriting is a dead tool. What are you gonna do with handwritten text? Scan it and convert to type text? How is handwritten text superior to typed text on notepad/word in any way? Can you handwrite at 100WPM? I can type a sentence with qwerty faster than I can write one handwritten word. The last thing I ever wrote in cursive was a love letter, --for novelty sake.
For those that need it for some special functions, like kdarling said, it is available to you via 3rd party.
It will never be native because it is incongruent with the iconic and elegant product design which is part of the consumer ownership experience.
