So, the free SharePoint Foundation Server is removed from SharePoint Server 2016.
That reminds me of an old story: a king hates all the bugs, worms and snakes, so he ordered his soldiers to remove all grasses and shrubs in the forest. "Anyway, we only need wood, right?"
What happened to the forest in the end?!
There are so many free alternatives. If Microsoft doesn't provide the free SharePoint Foundation Server, potential users will choose those platforms. Then, eventually, SharePoint will get less and less developers, administrators and users. So, its competitors will get bigger and bigger market share!