I am baffled why would they try to port this for Mac / Linux which already has SSH functionality built-in. It can make sense on Windows where there is no equivalent, by default.
Two-factor authentication is the reason. A use case is to access code from VSTS where two-factor authentication is a forced.
Not everybody who uses a code hosting provider like GitHub or Microsoft Visual Studio Team Services uses SSH. Some people use HTTPS for whatever reason (outbound corporate firewalls and proxies, ease of setup, familiarity, or just personal preference). And I would recommend that those users further use two-factor authentication.