The power in the 12 seems fine now, but it still may have an issue with throttling, especially in gaming. The air could throttle too, but the fanless design will definitely throttle during heavy use.
My problem with the ports is purely the amount. With the air I can hook up power, external monitor and 2 USB peripherals. Which I do all the time. I hook up USB midi controllers, microphones, audio interfaces, external hard drives, thumb drives and my iPhone for wireless hotspot (I find the Bluetooth connection slow sometimes). To even do one of these things and charge at the same time I would need a hub. And good hubs aren't cheap.
And I need to plug in a charger most of the time. I use the computer heavily, and I get 3 hours battery life at most. This is another reason why the iPad sucks as a Pro device, and making a MacBook more iPad like is a downgrade. Any heavy use tanks the battery fast. And then you combine that with not being able to hook up anything and charge at the same time. That's when the computer is actively working against you to solve problems. Not a problem with the Air.
The trade off in the air is the screen, but the screen still works! It does everything I need it to do, the only downside is a matter of perception not basic utility.
The 12" needs 3 USB-C ports for it to be worthwhile to me. The type of connection doesn't really matter, since that's just a change in cable, but the reduced quantity is the biggest problem to me. Especially now that one is needed to charge.
If Apple gives 12" 2 ports, 13" nontouch 4 ports, and 13" and 15" 6 ports, all the dongle issues would be solved. And I would consider getting one if the price was ever under $1200.