Unless I have missed something it looks like NMAP just checks the port is open. It would be really useful if the discovered service on the port (if possible) is also captured. this way we can find specific servcies and use them to trigger discovery with less false positives.
Example is vCenter. At the moment the only port for trigger files for vCenter is 9443. However vcenter appliances are not using this port and just use 443. this means to auto trigger these either we need SSH or SNMP Access to discover the host fully to get enough info to trigger or you have to try to attempt all 443 ports found.
Using NMAP you can return the port fingerprint
This information could be used to put in the port type more accurately and allow more directed discovery.