I have always, as a rule, UN-selected RAM and Virtual memory when choosing which volumes to monitor. I just don't see what I'm going to get from that monitor that I get elsewhere. PLUS, I really don't want to treat my memory resources like a disk. RAM gets fuller faster, changes more rapidly, etc.
Am I missing something? Do you have a compelling reason to include it?
Obviously the amazing engineers at SolarWinds feel this is a good thing to have, since they are selected by default when you discover a node.
I've never had a compelling reason to monitor them either. It might just be that they are discovered as part of the normal volume discovery, similar to how Windows machines have 20+ Miniport adapter interfaces for PPTP, RAS, etc.