I've never understood this rationale. Pretty much any feature can be abused by "less experienced" developers. I think you should never leave out useful features just because they could be abused--trying to protect developers from their own incompetence is never going to be completely successful and is rather arrogant at that.

I could see leaving out or modifying features that lead to a lot of mistakes, like manual memory management, but this is just a flag useful for debugging--you never have to use it and it does not affect your code at all if you don't use it.

Also, this feature is more like replacing unsafe functions with undefined rather than making everything dynamically typed. For example, it will always error if you run a poorly typed function, regardless of what argument you pass in. And, of course, if you're worried about your co-workers using this flag, you can just recompile without it and fix all the errors.