The color palette of the images in the blog post was adjusted to highlight areas of precipitation at the expense of intensity discrimination. Dark Sky itself uses a wider range, but it's still a similar blue to purple to salmon to yellow color table.
The reason we went with that over the standard green-to-red color table is because I personally find the standard colors to be jarring and more confusing to the casual user because of the increased contrast between intensity bands (at least, it certainly was to me back when I was a casual weather app user!)
The tradeoff is that there isn't as fine an intensity discrimination at lower intensities. In theory I can see how that can be a problem, but I haven't noticed it in practice.
The reason we went with that over the standard green-to-red color table is because I personally find the standard colors to be jarring and more confusing to the casual user because of the increased contrast between intensity bands (at least, it certainly was to me back when I was a casual weather app user!)
The tradeoff is that there isn't as fine an intensity discrimination at lower intensities. In theory I can see how that can be a problem, but I haven't noticed it in practice.