I've seen a few debates on weather or not BlackMarsh has a tower. This brings me to my question, what do these towers have to do with the provinces?

Nothing. They have to do with the psychology of the inhabitants, and how they interpreted the grand theatre of the convention.

Tower building was an Aldmeri thing. Doesn't prevent the Argonians from having an Axis-Mundi but it probebly isn't a tower.