I don't have much to suggest. For YAML, the use of whitespace, colons and dashes primarily emerged from usability testing with domain experts who are not programmers. In particular, testing was done in the context of an application that needed a configuration and data auditing interface, an accounting application. Even anchors/aliases worked in this context and supported the application's use by making the audit records less repetitive without introducing artificial handles.

Other use cases such as dumping any in-memory data structure from memory, perhaps out of a sense that we needed full completeness, actually didn't have any end-user usability testing. Round-tripping data seems in retrospect to be a diversion from the primary value that YAML provided.