Correct, but a LOT of developers today write code that eventually runs on Linux in the cloud. With WSL, such developers using Windows will not leave for OS X/Linux
Yeah I would agree it's a move against osx. I run debian on a raspberry pi3 don't even deal with Windows but this is clearly aimed at the corporate web developers where you have a macosx near monopoly.
I don't think that's necessarily true, I use Synergy on my desktop - 2 machines, a windows box for gaming and windows dev and a Linux box for most general uses including most dev work, ops work on servers, etc.
Something like WSL attempts to reduce the desire for this setup. Having things like real openssh work properly without cygwin is a major plus in my book.