That may be true, but how many shops do you know of that actually use HyperV? VMware dominates, Xen a ways behind, and Linux KVM and VirtualBox back aways. I don't think anyone actually runs VMs under Windows, it's rather the other way around.
Microsoft has been making some inroads with Hyper-V with mid-size businesses that are already 100% Windows environments - especially ones that haven't quite started down the virtualization path. Their licensing is attractive to these smaller companies, compared to VMware (at least the higher-end vSphere offerings). And it's Microsoft, which they're already comfortable with.
VMware destroys Hyper-V in just about every possible way at the enterprise level, but mid-size companies often don't need all the bells and whistles that vSphere offers, even as cool as they are.
If you're not part of the solution, you're part of the precipitate.