I'm sure in time changes will be made to allow us to bring them into additional content. It's a matter of figuring out how to do it on their end and bring it into a reality. For now they're adding these NPCs to parties only, but I'm sure in time more may be possible, the same goes with events. Right now they're adding them to Skirmish, this is current high end content, there's no reason to think they wouldn't be willing to add them to older content like Einherjar, Assaults, Salvage, or Nyzul, but it's a matter of time. Right now they did it with the most up to date content & I think that's a great choice. All the same I agree with this sentiment, I hope it's done sooner rather than later.