Whether you say docked is fast mode or undocked is slow mode is saying entirely the same thing in two ways.
Having only one resolution possibility doesn't fix the problem, though. Scale a 720-designed UI to 1080 and it's a bit blurry? Yeah, but if you just scale the whole game at 720 to 1080 then everything is blurry. But "sharp enough to not look bad at 1080, text legible at 720" is not a very hard standard to meet.
I think people are reading waaaay too much into this. The PS4 gets power, but would anyone say to do so is "charging" it? The dock will both provide power to the system so it runs now, and charge the battery so it will play unconnected later.
And whether the dock gives a power-up to the Switch is irrelevant to getting that. The thing is more capable than Wii U, which can do 1080p plenty fine.