You know I don’t play Cruci 
Can you try naked Cruci for me? with extra spawns. Should give a better assessement.
The issue I have is this:
As you noted, it is still a significant boost. If you take 3 random non set items, you are still going to be in a worse state than if you had gone for set pieces.
for eg; I love Fiendmaster’s Raiment and could use it in fluffy Squishy. I can also go for maybe Winter king helm + Mog shoulders or Fiend Flesh. But if I make that switch, my build will be much worse than doing nothing.
We don’t have enough non set legendaries to choose from when it comes to the slots that set items usually occupy.
Like when it comes to chest: we have 2 non set items to choose from.
Shoulders: Also 2.
Helmet: 3.
So, unless you were to go out of your way to choose Fiendmasters or Necrolords or something, you will still end up with the usual suspects.
And the reason why this hurts even more is because Crate announced that this is going to be their last major patch.
So I can’t even realistically hope for new items or such to come in the future to help actually promote diversity among choices.