The concept of mandatory custom properties are great, but as someone with multiple business units it would be huge to have the ability to mandate custom properties to a 'group' of nodes as opposed to system wide.
IE: Let's say I have a custom properties called 'Node_Function'. If the custom property is equal to 'Remote Router' then the following custom properties are mandatory. If the 'Node_Function' is equal to 'Data Center Switch' then this set of custom properties are mandatory.