> […] it turns out it lacks PLENTY of properties we usually work with. From 1400+ properties we normally use, there are only 480 on this page

This is intended. The list was originally created with the most common properties, and can and should be expanded any time when the need to do so arises. Unlisted properties will be moved to the end, in their original order (as stored in the database). If you find specific properties that should move up to one of the groups currently specified in https://www.wikidata.org/wiki/MediaWiki:Wikibase-SortedProperties , go ahead and suggest changes on the talk page.

As for the suggestions in your other mail: Even if I can understand that a more "nice" JSON would be – well – more "nice", I don't see what the specific benefit of that would be. As long as no specific use case arises I don't see a reason to invest resources in changing the current behavior.

Best
Thiemo