Hey, fairly successful (~100 player peak) server owner here.
I really don't see why Mojang feels the need to enforce the EULA. Even though it's well within their rights, I really can't think of any benefits on their side. It's not as though they're losing money when players donate to servers. In fact, the only good thing, in my eyes, is that they're trying to kill pay2win. While I do think pay2win servers are bad, it's ultimately the player's choice whether or not they donate to or play on a server (by the way, my server is NOT pay2win, even though there are perks that could be seen that way, I've balanced it properly). By enforcing the EULA, Mojang is driving away small, kid friendly server owners. As the name suggests, a kid-friendly server is mainly going to be populated by children. Since financially stable adults are the ones most likely to donate for the sake of it, or for cosmetic items, those small, kid-friendly servers (with 1-3 players on at any one time) are going to be punished heavily for their small player-base. Because server costs are dictated mostly by the number of complex, tick-intensive plugins and not actually the number of players (although players do factor in), a server with good performance, room to grow, and 50 plugins is going to cost around $40-$50/month. For anyone trying to make his own server, that's a pretty steep cost, especially considering it's only a hobby; new server owners rarely make that much money in their first six months or so. The bottom line is they're making it more difficult for kids to start their own servers. I was twelve when I started mine, and it actually motivated me to learn Java last spring. I doubt I would have kept it going if I didn't start getting donations, though. It's not all that fun running a server to make people happy when you don't actually get returns.
The only reason I can see Mojang doing this is to save face. After making the post about their EULA clarification in the summer of 2014, nothing has happened for almost two years, and I'm quite sure Microsoft started asking questions. To start enforcing it one and a half years after you first said you would seems a bit odd.
*EDIT* Don't get me wrong, even though I don't agree with them enforcing it, I do recognize that there's not much anyone can do to change it. I'm just speculating on the future and stating my opinion . Also, Blinque, that's not a good comparison. When you steal from a bank, you're actually taking someone else's money. When you're making money from a pay2win server, you're not taking money from anyone else. Again, it's the player's choice to donate and play on said server.
