The whole point is to want more. The spec has been, and will continue to be balanced around 60-75% up time as we go through the tiers. That's fine; if the spec is underperforming (I've seen nothing to suggest it is, quite the opposite), then it'll be buffed in ways that aren't Nightfall proc increases.
We must remember to, that the proc chance was cut to allow for the so called "perk" that increases Haunt duration. I don't think that was good design, shorter Haunts allowed more flexibility in the rotation between extending DoTs through Pandemic; and you actually cast Haunt more which felt good and more meaningful as you got more out of it. It is what it is though, these are things I complained about these things the entire Beta. Affliction though as a spec was frankly, otherwise broadly ignored for feedback.
If we could get a Glyph that reverts that switch, increasing Nightfall proc chance by 2% and cutting Haunt duration by 2s; I'd be all over it.