I'm a bit of a noobie here but that doesn't stop me from having a slight bit of an opinion (typical right?)
As much as realism, study depth, etc. are good things, VATSIM ATC (like real ATC) is ultimately a practical service with a purpose. Real ATC concluded that HPs were a good idea because they evaluated what their requirements and resources were and synthesized.
REAL ATC
Resources: Well-trained controllers, well-trained pilots, accessible dissemination methods, ramp controllers, cooperative personnel
Requirements: High traffic volume
VATSIM ATC
Resources: Amateur* controllers, amateur pilots, limited dissemination methods, no ramp controllers, sometimes non-cooperative personnel
Requirements: Low traffic volume
*No offense, I know VATSIM ATC training approaches the rigor of real world ATC training in most ways.
If you put the real FAA, airlines, airports, etc. into the "VATSIM world" in terms of resources and requirements, they would not come to the same conclusions that they have in the real world. The cost-benefit ratio is out of whack. The fundamentals of ground control probably best serve the situation while remaining emotionally satisfying to VATSIM's mission.
The best way to implement HPs (I think, at least initially) is to make agreements with select VAs who promise to ensure their pilots are HP certified. Only "Class 1" VAs, and their pilots, as shown in the flight plan comments, would be able to be given such hold points. Similarly only select airports should require higher-than-standard knowledge from their controllers for HP ops. OAK_GND might not be a HP ops position while SFO_GND is.