Yes, you're right. And it is not required. But I wanted to do it qua specificationem ;9
I'm using AcitveState Komodo IDE 7 Alpha with inbuilt syntax-check for Node and it notified me, that if it is run in a strict environment, it'd be against the rules. Quick check @ specification of ECMAScript and yes, there it was. All I wanted to do is stay safe by following the specification, who knows what V8 brings in time.