>Couldn't you have just extracted the pieces you cared about ahead of time? Sure, but if you discover this desire later, you now have historical data to change

>Couldn't you have just extracted the pieces you cared about ahead of time? Sure, but if you discover this desire later, you now have historical data to change and application behavior to change and database structure to change. And repeat all that when you discover the next piece of more-useful-than-anticipated data. Or you can just `alter table` and be done with it.