ONE: If the iPad ran Mac OS X, it would do so in a limited capacity anyway. Just like netbooks can't run higher end apps, the iPad wouldn't be able to run them either. Not only is the CPU lacking, but the iPad has very little RAM compared to multitasking desktops. It seems contradictory to me to call something "full-featured" if it can still only be used for a subset of tasks. Keeping Mac OS X off of the iPad means that all of the software will be built specifically for the device, instead of being built for generic hardware. When the limits of your device are known, software can (and will) be tweaked for those environments. If the iPad ran Mac OS X I really don't think you'd be hearing about its relative speediness—at least not in a positive light.
TWO: Speaking of subsets, if you are a Mac user you have to realize that iPad users may or may not share your affinity for Mac OS X. The iPhone OS is where all the attention is right now—consumers and developers. Putting Mac OS X on the iPad would not only limit the target audience to Mac users (or those interested in switching), but it would also curb developer enthusiasm. There is no "developer gold rush" when it comes to an established platform like Mac OS X. It would be a foolish move for Apple not to capitalize on the momentum of the iPhone OS.
MISC: Keyboard shortcuts are an important part of mastering Mac OS X. They are also one of the reasons I prefer Macs to PCs. Unfortunately, a device without a keyboard isn't going to benefit from keyboard shortcuts. That alone might very well make me pass up a MacPad for a MacBook.
It boils down to this…
- Option A: iPad + Mac OS X = Bottom of the line $500 Mac portable. OR High-end $2000 Apple designed Modbook
- Option B: iPad + iPhone OS = Premium $500 multi-touch device