Because blue is better for reading. This exists beyond SMF; see Tails, Windows 7. This light-dark blue theme rests your eyes. If you don't like it, change it with
BPIP.
Thank you. I did not know it, It really is. I have wondered many times why people use a black theme on Linux systems. Somewhere they wrote that this is the most readable and tireless topic for the eyes. But for me, it didn't work at all. just like the switching action for night mode. Also annoying are all sorts of flickering banners, with a bunch of distracting ads.
So yes, the blue interface is very readable. But if you think about all the OP's preference for orange, one would be horrified at what color shades exist in being such a bitcoin fanatic.