Totally agree with division into modules lowering complexity (provided it narrows inter-module communication). An interesting idea, that a DSL is way to do this

Totally agree with division into modules lowering complexity (provided it narrows inter-module communication). An interesting idea, that a DSL is way to do this. But designing a language is hard, including a DSL. Even for experts. e.g. Codd had two attempts at a language for relational algebra, but "mere mortals" couldn't use them. Mathematicians create new notations at the drop of a hat, giving their own definitions to common terms willy-nilly, but this can be an impediment to collaboration. OTOH, there's an advantage of having many different attempts at a language, inspiring and cross-fertilising each other, til eventually settling on a near-optimal design (if everyone designs their own DSL, this doesn't happen). In practice, you get one group of people experimenting like crazy - academics, visionaries, hackers - and a huge majority that waits to see if something emerges that they can standardise on. Meanwhile, experiments continue. (This is basically the "technology adoption lifecycle".) The ruby community develops new DSLs very quickly, in the form of frameworks. I get the impression the rapidity of change is challenging, but the improvements are worth it.