Pretty bizarre. He says he is "favoring ease of development over performance," but the best way to ease development would have been to use a well known language like JavaScript or C#. Those are the two scripting languages in Unity as well, so it would have immediately worked with Unity developers, and C# isn't far off from Java for one of the other biggest languages. Kind of sad VR development is going to hobbled like this.
Ease of development for a programmer is a different thing than ease of development for a company, the latter usually means you can hire tons of cheap programmers to crank out code. Carmack simply decided to choose a powerful tool instead of a popular one; a choice which I applaud and wish more people and companies would make.
"over performance" doesn't mean "with complete disregard to performance". You still need to hit >= 90fps with zero hitches and zero dropped frames.
A less performant scripting language can be a wise choice if the the productivity gains are sufficient. However that language still needs to hit 90fps with no dropped frames.
