I think all mentioned tags should be merged to windows-phone.
Sure, there are significant differences between the versions. But do we realy need that distinction?
Most questions posted these days address developing for WP 8. But the question could be relevant for earlier versions as well. If the poster is unaware of that, he'll probably tag it with WP 8 where WP would be a better tag. The community could correct this but why would we lay this burden upon the community?
Suppose the tags are merged and a developer has a question related to a specific version. He can only pick WP so the tagging system obscures that it his question is related to a specific version. Is this bad? I don't think so. The question and the answers can address the fact that it relates to a specific version.
- Clean tags
- Just one tag to follow when you are intereseted in Windows
- Easy to use for new and seasoned developers
- Future proof (more or less)
By the way, our highly fragmented and frequent updated friends from android use just one tag. I'm not sure if that should be considered a pro or a con... B-)