As a geek, you'll adapt because it's new and cool, and as a user you'll adapt because the new interface is wedded to technology which accomplishes something useful (being able to IM from anywhere you have cell phone reception).
It's all market-driven. People are willing to put up with 12 key interfaces because the need for IM anywhere is greater than their need for a keyboard to do it with. I don't think anyone really _likes_ a 12 key interface, but if that's the only thing that will provide that connectivity, that's the best there is right now and people will use it.
On the larger topic of the pay-by-use Internet, I agree that it's not a great trend at all. Per-Kb SMS charges are why I refuse to sign up for one of the cell phone messaging services even though I've thought of a few times when IMing on my cell would be useful and viable while holding a voice conversation would not.
However, when you think about it, most use of the Internet is currently pay-based anyway. It might be flat fee (like an ISP) or it might be embedded in some other service (like a degree program at school, or employment at work), but you're paying for it one way or another.
"Free as air" e-mail is a myth. It's an illusion created by flat-rate plans, though of course every e-mail you send makes your per-message charge lower. Here's to hoping that people in the market vote with their dollars as soon as flat-rate SMS is offered in the U.S.
(A Dvorak keyboard user :)