I think of those sorts of things as paradoxical people requirements. To wit, only people interested in new languages spend lots of effort building new language

I think of those sorts of things as paradoxical people requirements. To wit, only people interested in new languages spend lots of effort building new languages (and their associated ecosystems). People who have been using an existing language for years, long enough to internalize the design decisions and flaws, have little incentive to stop using something they're an expert at, to build something new. Ergo, the person you really want designing a language and ecosystem is someone who's used existing art enough to be an expert, then decides to give it all up, start from scratch, and do something harder. There aren't many of those people.