Fair enough, however regarding massive multiplayer requirements most game shops are anyway using Java or .NET on their backends, as you can easily check going over their job adverts.
As on the client side, proper coding plus offloading stuff into shaders already goes quite far.
And even in the debatable point that Java isn't the best language for any kind of game development, well maybe Mojang would never have taken off if Markus had decided to prototype the same in something else.
Nowadays the Java version is only kept around due to the modding community, as the C++ version is found lacking in this area.
As on the client side, proper coding plus offloading stuff into shaders already goes quite far.
And even in the debatable point that Java isn't the best language for any kind of game development, well maybe Mojang would never have taken off if Markus had decided to prototype the same in something else.
Nowadays the Java version is only kept around due to the modding community, as the C++ version is found lacking in this area.