A language is nothing but the code it engenders. Bad code, bad language.
A language that evolves "is" the new code that is written in it, with deep legacy substrata written to previous versions. You can have a good top level but an embarrassing legacy. We should always strive to make our legacy embarrassing, because that marks improvement.
If ten-year-old code in your language is not an embarrassment, your language is stagnating.