I only see value for Windows as a desktop OS, and I think the intent of WSL is improving the dev experience on Windows.
If you need a high quality Linux server, why not just run Linux?
If you need a high quality Linux server, why not just run Linux?
If you imagine WSL for Windows Server not as competition for CentOS and Debian, but as competition for "enterprise Linux", then you can have a compelling sales case for enterprises which are already heavily invested in Microsoft, i.e. with extensive Active Directory and Office 365 deployments. Why purchase two support contracts, one from Microsoft and one from Enterpise Linux Vendor X, when you can buy just one support contract from Microsoft and still run everything you need?
I think it would be really interesting if MS competed in that space. But 'nix sysadmins don't want to worry about maintaining a Windows instance concurrently with their server instances (assuming the only facilities they need are what 'nix provides). Microsoft having Windows attached to their Linux distribution is a net negative, in my opinion.
Edit: Formatting