Nice to know I'm not the only one who bothers with this stuff.
The key points I was hoping to address were
Perhaps the most important part is to get a business stakeholder to be a driver of the process. If business profitability relies on being able to explore and analyze data then you have to know what you are exploring and you can only do this with a useful data dictionary.
For me agile doesn't say "no documentation" it says "only produce documentation that has business value".