As someone who has spent the past 25 years in the Department of Library Science, there is more than political correctness when the terms we use to refer to school librarians morph. While media specialist does include more of the librarian's tasks, the term teacher-librarian is also an indication of the true role of the librarian. Information specialist, school library media specialist: there are many labels that could be applied. Maybe labels are not that important, but they do tend to define the boundaries of the job.
I am speaking at a conference of librarians in August about the dual nature of their roles, and I have been giving a great deal of thought to the concept of "balance." Just the mention of this term, though, makes me flash back to the "balanced instruction" debate about reading/ There were multiple definitions for "balance" as well back then (and there still are within CCSS frameworks). Balance could be seen in ways like the following:

Here balance is precarious, a balancing act if you will. If we are so concerned about keeping balance, I doubt we will accomplish much (and this applies, BTW, not just to labels but to issues such as CHOICE in reading). Here is another view of balance:

I do not care much for this either as it appears that balance is sort of staying in the middle of that which is approved and disapproved. Finally, there is this view of balance:

While I am not totally happy with this vision, it still comes the closest. It suggests proceeding carefully, perhaps tottering a bit along the way, but finding a way.
This is still a work in progress, and I thank Russ for giving me some more fodder for my thinking.