You do realize that the iPad Mini won't ship until next Friday, and that people may want a head start on testing their app on a smaller screen.
And additionally, I'm sure there are a lot of small developers who can't afford to buy all the devices their software might eventually run on.
I've only just submitted my first version with in-app purchases to the store but if you get it now you will be grandfathered into some features when the update lands. http://itunes.com/apps/fastlists
I would have ordered the mini if it had more pixels (even at a higher price and lower battery life) but as it is I think I'll skip that version.