Minecraft was not big in education as a product until after MS bought it. It was being used by educators without official support, sure, but it wasn't an actual service. They completely changed the business model and expanded the functionality of how Minecraft was being used in that sector, and used it to push their other education focused products including their education specific version of OneNote.
That wasn't the only reason they bought them, but it was a big part of it. Chromebooks were making huge inroads into the education market at the time, and this was part of their response.
Yea the surface go and now laptop go are also part of the play into education. Microsoft gives away a lot of educational office licenses. The problem is they are too late to the market with the hardware. Chrome books suck. we all know it and the ones they give students really suck they are $200-$400 machines. The problem is windows is not light weight. It runs worse than chrome os does on that ultra low end hardware. Even the laptop go is to expensive for the market but at least they are getting close. I really think big/little intel and amd cpus could help them crack the market in a way they can't right now.