There not a single data structure that fits all needs or is the right one. The usefulness of a data structure depends on it's use case. A delicate balance between the data that is exposed to the client and keeping the response as small as possible. If your goal is to populate a dropdown box with some data it is not necessary to send all available data to the client.
That's why various MXMS API's provide the same datasets in different formats. Actions available might be limited on some API's. Some API's may only be read-only for example and do not have any update methods available.
Objects are exposed to an API based on the data available for an object. E.g. An object that does not contain any latitude and longitude information is not exposed to the GEO API. Want to know more about a format? Select one below!