Before the iPad and iPad mini, they had the iPod, iPod Nano, iPod Shuffle, iPod Touch, and then the iPhone that could do everything that the iPod Touch does. Guess what? They all still exist today.
So they have a recent history of starting with an iconic product and then diversifying product offerings from there. I guess that does give their customers greater choice (which is not always a good thing) but it also complicates their production process. Since they're used to doing this, the iPad mini as a diversification of the iPad is easy for them to digest. I still get the feeling they're confusing their customers and complicating their jobs. Signs of a big company.