[lelandbatey]

I don't share the disgruntled feeling toward the color.

The new color is #0366D6, while the old color is #7FA5CF. The new blue color is far more saturated and is much less light, but is actually still a pretty big step down from ultra-hard blue #0000FF. IMO, it's much more readable than the previous blue and stands out nicely.

[edutechnion]

Exactly. The 0366D6 against the hover background of f6f8fa provides a 5:1 contrast versus the old 2:1 contrast.

http://webaim.org/resources/contrastchecker/