While I guess they could bundle the Windows 7/8 Calculator with Server 2016, that would make server and desktop Windows different (for a feature that both include).
To make another guess, a lot of Server/LTSB users might actually like an even older Calculator:
To make another guess, a lot of Server/LTSB users might actually like an even older Calculator:
https://news.ycombinator.com/item?id=10791667