In what use cases I will need WSL
Cygwin has existed since... Well for as long as i can remember. Its basically the same, except for the filesystem being a mounted tarball. Cygwin is however, limited compared to .deb / .rpm etc - ports must be made to .exe for each package. As for myself, it comes in Very handy when developing and with a unix repository manager handling installs, its very fast to setup a platform with all those capabilities we're used to on a linux host. Some things are not available on Windows (.so vs .dll) and vice versa. Just my 50 cents