Please consider the need of defining a minimum set of mandatory elements and attributes to consider that an IATI XML file is correct (the Core).
Many other specifications do it: for example Dublin Core, ISO 19115 Geograhical Information Metadata, etc...
To my mind, the last comments about the differences between data registered by different providers, confirm this requirement.
To compare data, it is necessary to have the same basic information filled in.
This is perhaps the most important thrust of Version 2.01. Separate topics have been created for each targeted element.