Microsoft just wants to avoid press of kids getting groomed or seeing adult content on Minecraft servers. Stuff like this is bad for a brand that primarily targets kids as new players and could get them into hot water with regulators.

I personally believe that they probably should add parental controls to Minecraft so parents can control what if and what kind of servers kids can join. I also believe more control will put more scrutiny on Microsoft since I haven't a lot of negative press about child safety in Minecraft especially in comparison with Roblox for example.