Ross Rubin has a solid post about the differences between Surface and iPad, but this bit about value to developers is key:
That said, the long-term incentive for at least Mac developers to adapt the full power of their apps for the iPad seems clear. The level of mastery Apple has achieved in silicon–combined with the emerging ability to bring iOS apps to the Mac–points to a future where the Mac could more or less be an iOS development target that uses a trackpad instead of a touch screen.
I look at it like this, if you make a Mac app that doesn’t have a full featured iPad (and iPhone if it makes sense) app, then you are basically waiting to go out of business. You’re working in a marketing that is shrinking, even as sales of Macs grows. The same is not true for the iPad.
Lastly, I’d be remiss in not quoting this bit that made me chuckle:
Even today, someone who uses an iPad as their main computer is viewed as a kind of avant garde minimalist.