It would be nice to have the ability to set default values for custom properties, outside of modifying the database columns directly. While we are able to work around this, we are at risk of losing support when performing upgrades etc. Not having default values results in NULL for columns of type nvarchar. Any alert trigger queries that contain logic around that property can create some undesired results, for example
select *
from nodes
where CustProp1 <> "BadNode"
will return 0 nodes even if the table has 50 rows with a value of BadNode in the custom property and the other 50 rows with NULL.