IIRC this suggestion was raised by @Marek_Hulan, so I’ll let him elaborate, but the general gist was that the importer should just dump a json blob into the DB and the parser will handle everything regarding extracting information from it.
The idea here is to allow Foreman to gather information from multiple sources out of the box, without requiring additional plugins that add complexity which might not be useful for everyone - for example, puppet class/ansible role assignment to hosts and hostgroups, variable handling etc.
Additionally, if we have multiple parsers in core, there might be a chance to combine logic that is duplicated between the different parsers.