This is an advantage depending on the projects and organisation. For instance if features need to be demonstrated or prototyped on a test env. for some time be

This is an advantage depending on the projects and organisation. For instance if features need to be demonstrated or prototyped on a test env. for some time before they are green lighted to be fully baked, loosely typed languages are ideal. You get the speed of prototyping, and all the heavy cost comes after the main parts have been validated. It's less painful than having to do prototypes after prototypes in a more rigid language. But of course this advantage disappears when working more in small waterfall iterations, where everything is basically set in stone from the start.