There are a few fundamental differences between these languages, but it's just plain wrong to say that any of them are not "structured." Did OP mean "schema-less" instead? Because the only fundamental difference at that level is that XML has a built-in mechanism for metadata referring to a file's own schema, while in JSON (and I believe the others, even though I've used them less) the schema is not linked from within the file itself. You can still verify the schema of these languages, though, just as you could with XML. And once you've verified the schema, local code can do stricter validation to make sure things hang together properly, that values are within limits, and so on. After that, I expect modern tools like Terraform and CDK to check with the target platform that the scheduled change can be applied before trying to change anything.
That said, OP has several valid points:
- Many projects try to make a microservices architecture long before it's needed, even in projects where it might never be needed. I suspect some people think microservices are actually easier to maintain, since they are smaller pieces, but only extremely trivial or shoddy microservices will be easier to maintain than a corresponding monolith, because many things which are well-understood in a local setting are much harder to do in a highly distributed setting, simply because the infrastructure is now a bazillion separately managed pieces.
- The feedback loop can be abysmal. Without any easy alternatives to do "local cloud" deployments, having to wait for several minutes for feedback about a tiny change is frustrating in the extreme.