Since Steve Jobs came back to Apple in the late nineties, numbers appended to product names were verboten. In the WWDC ‘98 keynote, he showed a slide of all the Mac model numbers there were at the time and how confusing it was to tell them apart. From that point on, there would be no numbers suffixed onto any Mac, and other hardware lines like iPod and AppleTV would never get them either. If necessary, a generation number can be used in support documents.
And then came the iPhone.
Apple famously got the carriers to relinquish a huge amount of control when the iPhone was introduced. But I wonder if one of the very tiny concessions that the carriers got in exchange was that each model of iPhone would get a unique model name. I could definitely see AT&T balking at selling the brand new "iPhone (third generation)", and certainly not the "iPhone (2009 edition)".
I think deep in Apple’s marketing’s heart, they’d still prefer to only sell an iPad Pro, an iPad Air, and an iPad Mini. No numbers. But in 2011, the seal had been broken for product enumeration by the iPhone 4, and that opened the door a tiny crack for an "iPad 2".
Having numbers makes sense when a product line gets larger by selling last-year’s model alongside the new one. It’s easy for Apple Store employees to say that iPad Mini 2 has these features and that iPad Mini 3 adds the Touch ID.
But that explanation doesn’t work for iPad 2. The original iPad, practically dismissed in this keynote as much too thick and heavy, with a hideous case that made it even thicker and heavier, was consigned to history and pulled from store shelves.
My theory for the real reason why this iPad wasn't called iPad (second generation) is much simpler. The running theme of the keynote was "2010 was the year of the iPad. Come see what 2011 will be the year of"
The only punchline that works is "iPad 2."