I feel as though it would be easier if, for security reasons, you were able to import custom file types and set up properties and different editing methods for each one. For example, instead of creating multiple points in an empty GameObject and trying to name them different things, have different IDs, and etc… You could just have an empty GameObject with a component and a referenced KMP that stores all of this. Same thing with a KCL, or collision. Looping audio files, such as a BRSTM, BCSTM, and BFSTM, can be used instead of having a simple audio source. I WANT THIS IN 2017.3!!
The official place where Unity Technologies wants us to submit feature requests is http://feedback.unity3d.com
That being said, UT did add an experimental API a while ago to import custom file types:
https://docs.unity3d.com/ScriptReference/Experimental.AssetImporters.ScriptedImporter.html