Interesting point. I think that's also due to some influence on Apple's part, because Macs were never released with sequential numbers like the iPhone.
I'd suspect Apple is purposefully trying to disassociate the iPad with the iPhone and realigning it with the Mac line by changing naming conventions. If that's the case, this post is pretty good evidence that it hasn't really worked out so far.
Right, except for the fact that Apple lists it as "iPad (3rd Generation)", not "iPad (Early 2012)", so if you're right, they're trying to align it with the iPod rather than the Mac. Simple product line => simple names => simplified purchasing experience. No need to read anything more into it.
Generally speaking, I referred to my iPad 2 as an "iPad", and when not in the process of purchasing accessories or arranging repairs, I commonly call my "MacBook Pro (17-inch, Early 2011)" a "MacBook", "Mac", or, most frequently, "computer", in line with the common practice of most everybody I know, technically-inclined or otherwise, unless there's some need to either disambiguate or brag.
I'd suspect Apple is purposefully trying to disassociate the iPad with the iPhone and realigning it with the Mac line by changing naming conventions. If that's the case, this post is pretty good evidence that it hasn't really worked out so far.