Yes I know exactly how many points Lords are, I just wasn't sure if I was allowed to post exact points costs. Also cause I know the points of one, I also know the points of 5.
While I really like heralds, I don't think I need them. In a more casual list I will absolutely run heralds. But here, they can't keep up with the princes and I really don't need +1s from them. One of the slaneesh princes, with intoxicating elixir and diabolic strength, makes for s10 and 9 attacks. That combined with all the smites allows me to take down hard targets.
Yes, I realize they do not become actual demon princes. While not technically correct, it gets the summary of what the model does down pretty well.
Your missing the point of them. They are dirt cheap, so who cares what happens to them. They are smite batteries that hid behind cultist. Is one smite a big deal? No... But 5 smites become a big deal. "But you have to target the closet model!!!" So? Take 10 wounds, no saves. And most people can move their models well enough to get what they want to be the closest model to be exactly that.
But if they perils they take D3 wounds! Again so? They can't die from it (remember they should be hiding in a cultist bunker), so throw your newly promoted Lord into the thick of combat. Who cares if he dies. He cost 30 points...
All that being said, I'm inclined to go with you on this and find something different. Against different things I think the Lord works great, but in my meta I think I want havocs, drones or heralds.