If authors can not use powerful tools, they cannot create powerful libraries for other developers to use. Everybody is then pushed down to the low expressiveness level. Case in point: Golang until recently, Java before version 5. Copy-paste programming is as prone to bugs as stringly-typed programming.
If there needs to be a strict separation between powerful tools and easy tools, using two different languages works well enough. Many game engines allow level designers write small Lua scripts, for instance. Or the whole Visual Basic thing which allows to glue together powerful COM components. Also, nearly every templating language allows for simple data manipulation (iteration, filters) while not being Turing-complete.
(That works until the users of the simple glue language require enough features for the glue language to become a principal tools for developing increasingly complex things, and we're in square one. Could have started with a proper language...)