There's only 15 million of you, if I recall correctly, and most of them have already coughed up more for the retina one. But there are 70 million iPad 2's and 3's, and I read on MacRumors that Apple expects to sell at least 10 million "mini" iPads in Q4 (not to mention a few more millions of iPad 2's and 3's, and a gazillion more iPad 4's when they introduce them), and almost all of them (except a few who are cranky about the maps, which would soon be forgotten when Google releases its maps app) are on iOS 6.
I too am starting a new iPad app, and it'll be iOS 6 only - because it'll be released early next year, and because it's really, really easier to only target iOS 6 as there have been many improvements in the APIs that literally cuts development time in half.
I have a first generation iPad, too. I had some magazine subscriptions on the iPad that I got for free because I was a subscriber of the physical magazine. With the exception of traveling, I preferred the real magazine. The metaphor of how ads are displayed in physical magazines, paging, etc. didn't carry over well for me in the iPad.
While travelling, I thought it would be cool to have access to a library of magazines to peruse. I ended up mostly just watching videos.