But ... we did, and do. It's called HTML. It allows you to send back structured data in a client-agnostic way. It's just that it got bastardized to the point that people will send the data in a way that only certain clients can intelligibly render it, and then, only in a way usable to people without certain disabilities.

It's not just a technical problem, but the social problem of how you get people to keep using that API, and not extending it, and not breaking it in favor of some different purpose (like ads)

Whatever API for web data you propose, I can tell you exactly what will happen to it:

1) Initial clients are geek-designed and geek-friendly, and render the data intelligently.

2) This API gets popular for not having all the cruft.

3) Some genius discovers they could add some cutesy visuals and effects if only the standard were extended, and targets the clients that handle these extensions.

4) Eventually, only those clients are cared about, and you can only make sense of the data with those clients and if you don't have disabilities.

If you want to make progress, figure out how to eliminate that dynamic.

Earlier threads on this point:

https://news.ycombinator.com/item?id=30727026

https://news.ycombinator.com/item?id=20224961