I really love developing on sql server, but...
From memory I remember when they "acquired" the source from Sybase and one of the selling points was that they could strip out all the multi-platform complexity from the source code. Being windows-only meant it was simpler, less complex code, faster and less buggy.
It also confuses my view of what MS has been doing. Maybe Azure is more important than Windows now? Its going to be kinda weird to see SQL Server on Linux in Azure.