I strongly disagree. I think this is the WORST thing ever to happen to Minecraft, including clay blocks. Most servers are going down, because people don't donate to servers without expecting something in return. As for cosmetic stuff, most people don't give a darn about that.
I only wonder.. Why? Why would Mojang make this negative move against the community? If you actually think they care about what is "fair" then you're kidding yourself. If you don't like what a server is doing in terms of selling stuff, don't play. Eventually, that server will survive or die by the will of the players.
Anyway, the server I play on is small scale enough that this won't affect me. The community is tight-knit enough that Mojang won't even notice.
One word: Realms
Read between the lines. They are not killing servers, but surely limiting their ability to make revenue (which translates into programming, new mini games, bandwidth) will make realms more desirable. If you can't beat your competition in a fair race, kick them in the kneecap before the race starts.
I don't really have any dog in the race. Either way works, but I do feel it will limit future features and also even if it is the correct thing to do, it seems like a bad PR move. Without the industry sprung up through servers/youtubers/modders I think minecraft would still be successful, but nowhere near as successful as it s today. I have personally got 6 people to buy minecraft for the multiplayer experiences on a few different servers.