12" tablets are fine and dandy, but they're not portable in the same way as 7" ones are. I've owned both, and I used to look down on 7" tabs as lesser to larger ones, until I got one. I find that, for me, they have completely different uses. 7" tabs are for carrying around, to comfortably read websites/email/social media. They're like phones in that you don't do stuff that you could not also do on the phone, but the added real estate is greatly appreciated. 9" and above tablets on the other hand are much less portable, and while you can carry them around and use them everywhere, they're most often used when you're at least sitting down somewhere where people won't disturb you, like your comfortable sofa, or a coffee shop. They allow you do to things that are not really that doable with smaller tablets or phones.
This means that 7" tablets can look and function as large phones when it comes to UI and external looks, and still do their function. It's perfectly right, and they ARE expected to be used in almost the same way as phones.