As far as I understand you position it as a feature, but, unfortunately, this is more like a bug.

I think it's a good way when 3rd party solutions don't have references to another 3rd party solution.

We don't use WebActivator in our projects, so we can't use MvcSiteMapProvider library without the modifications to the source code.

I think it would be better to have a separate module that implements WebActivator features into MvcSiteMapProvider.