Informal vs. formal and the gradient between them is always going to be an issue in any language, especially when comparing languages.

French also has more built-in structures for formal address/politeness, though many of them are being left by the wayside just as we left feudal lordships with a peasant class.

For what it's worth, I'd say that the more "stuffy" version of "de rien" in French would be "il n'y a pas de quoi".