Here's a guess why that "Never" option might be there:
At certain code levels and certain hardware versions, Cisco incorporated new virtual interfaces based on new RFC's. They duplicate (and triplicate) the physical interfaces that NPM can discover, and have names that include "controlled" or "uncontrolled".
The details about those ports are associated with planned security needs, and can be found here: http://www.ieee802.org/1/files/public/MIBs/IEEE8021-SECY-MIB-200601100000Z.txt
Suppose you want to monitor physical interfaces on a switch (Gi1/0/1-Gi10/0/48), but not the duplicate interfaces (Controlled and Uncontrolled) for each physical interface that shows up on a discovery. You don't want them eating up your Node/Element license count, and you don't need your NPM server's internal resources spent monitoring or discovering those interfaces.
Telling your Orion product to "Never" select/manage interfaces that are Controlled or Uncontrolled would sure be convenient.
Without that "Never" option, you may have to manually select the desired interfaces, or unselect the Controlled and Uncontrolled interfaces. That's a lot of clicks if you've got a fully populated 4510 chassis switch. And even more if you have several dozen of those chasses, or lots of 8-deep stacks of access switches.
But maybe the option is for something completely different.
I've shared what I've learned about the new Controlled and Uncontrolled interfaces in an answer to a Thwack question here:
Re: Unknown Additional Interfaces as Uncontrolled/Controlled on SUP8