How is that different from how node v5 supports additional ES6/7 features that don't work in node v4? In the end you can only rely on package authors to be aware of their targets' capabilities and code to the minimum baseline accordingly.
Suppose you could transpile what is possible, then throw errors otherwise, however that would involve parsing each file in an NPM module which is probably an unreasonable task performance wise.
It's easy to install NodeJS 5 with v8, it is however unacceptable to be required to switch to Windows.
This could change if they get around to porting it completely. For now the only thing they've committed to in the next 6 months is porting the ChakraCore interpreter(but not the JIT).