Back in the day when I first started getting into dispatch, the theory relayed to be was the High Altitude Waypoints (HARs) would allow, and mentioned ealier, greater flexibility for both flight planning and dynamic routing for weather or traffic. There's a system to the naming though I can't be bothered to learn it. In practice, "most" of us when building routes around weather tend to use VOR's to work with. It's easier and habit to know where SLN (Salina, KS
) is on a map versus KK54C. PIlots also tend to be way more familiar. Controllers, from my experience, still deal with VORs or named Waypoints (like KIRKE for instance). They're more apt to give you a dct to BFF (or often a dme/radial off a VOR) instead of dct to KD72W for weather avoidance. Old habits die hard.
Another issue we run into is Database memory space. ONce you start throwing in all the info for new RNAV SIDs and STARs you start running out of memory quickly (keep in mind I think we're still using Commodore 64 memory discs).