If you make a new language that's exactly like the old language but has a slightly tweaked syntax for one or two little things (e.g. changing the capitalization of the name of the string class), you're forcing lots of programmers everywhere to rewrite their code in the new flavor. You're forcing companies everywhere to spend more resources on hiring, retooling, etc. And you actively contribute to bitrot by weakening the incentives to keep old code running as-is on newer runtimes, because "no-one writes such code nowadays anyway". It's basically a lot of waste that could be avoided.

The jump from C++ to Java was big enough: it introduced garbage collection, proper modules, proper strings and other nice things into the mainstream. The jump from Java to Python, if it happens, might be marginally big enough to merit rewrites (we gain many nice small-scale constructs like dicts, generators and list comprehensions, but lose the IDE tooling and guaranteed-correct refactorings enabled by static types). The jump from JavaScript to Dash doesn't seem big enough to justify all the busywork. Please come back in five years with more shiny things.

...A man can dream, can't he. Obviously the big guys will keep introducing new languages where a new library or a new runtime could've done the job. They have incentives to do so. But it's not so pleasant to the rest of us.

You'll note that I have avoided using the word "innovation" so far. That is because genuine language innovation generally happens outside of the mainstream and takes decades to percolate. For example, the idea of list comprehensions is older than I am (NPL '77). For that matter, so is the idea of lazy pure functional programming (SASL '76), and the idea of parameterized types (ML '76), and any number of other ideas that people mislabel as "innovative" to justify creating new languages today. Adding 30-year old features into curly brace languages, bit by little bit, and forcing us to rewrite all our code at every step doesn't sound to me like the noble practice of innovation. It's more like a big coordination trainwreck.

While there is such a thing as punctuated equilibrium, I believe you'll find that evolution is largely incremental in nature. Seems like evolution simply has to happen this way, whether we're talking about biology or technology, including programming languages.

You are aware that many people still write C++, yes?