I love HQs - my main has done all but one. My T7 alts have done maybe 5 or 6 between them.
The main problem is that levelling is so much faster now that its unrealistic to expect players to spend a lot of time on HQs for items that will quickly be outlevelled. One solution is to reduce spawn times etc etc, but I would prefer to see T7 "upgrades" to HQ items. That way, the quests would have a purpose in T4 or T5, people would run their alts through them, or be prepared to mentor down for them, because there is an endgame function to them. And it would provide some much needed new quest content at T7.
If there were upgrades, I think players would (in general) be less resentful of long camps. Ths would reduce the need to make the quests easier/shorter/soloable/morefun/whatever.