I suspect that the reason that we're not getting the new 3DS yet is for the same reason that we didn't get it before - the North American region hasn't yet met whatever target goal was set for selling original 3DS systems, but people are getting antsy for the release of the new one (especially for MH4U), so they're finally giving it to us. I bet that the 2DS will remain the cheapest, the old 3DS will price-drop to come in at a midrange bracket, and the "elite" model, the new 3DS XL, will be the high-priced one. I figure that we'll get the new 3DS once that old 3DS stock sells through. (At the same time, I'd like to see North American 3DS to 3DSXL sales figures - When I worked at [video game retailer], I seem to remember that a lot of people opted for the bigger screen for the DSi, or went for the much cheaper Lite. The regular DSi didn't really start moving until the Lites were gone.)
As for the power adapter... it's what they did in Japan. It sucks, but it adjusts whatever their profit margin is. On top of that, a lot of the people who will care about the few games that the new 3DS can play that the old 3DS cannot (to date, isn't that just the Xenoblade Chronicles remake?) are people who will be upgrading from the old 3DS/XL, and therefore already have power adapters. People with an old 3DS/XL can still play 99.95%(I made that number up, but whatever) of DS/3DS games.
And to the people trading in their systems to buy the new ones and therefore have to trade their power adapters too - they're just SOL. Used game and hardware sales don't necessarily help Nintendo.