[electrichead]

To be fair, that was kind of an accident. Xmlhttprequest just kind of sat there until somebody else came up with a use for it.

[emn13]

It's an accident of history that's it's primarily used for Json and not Xml, but you can hardly argue that the API itself was an accident.

Frankly, the importance of json in this matter is pretty minor anyhow: if it hadn't been around, you can bet some nice JS library would have come up with a different way to easily decode server data into JS objects. The scripted communication was key.