“Why are we using a data format where this is possible at all?” Because it was designed from an authoring POV, not a network POV. It should have been designed for both, of course.
“The new API is pretty much the same, except that it’s now accessible via https rather than http and it versioned as well”. Versioned?! Oh joy. Remember kids, these are *Web* APIs, and on the Web, cool URIs don’t change.