It doesn't really matter if co-op has already given us a version of this, because we'll have way more utility after this cones out than we did before. Single play dungeons have twelve possible actives, co-op has twenty. I'm having a hard time buying that this is going to be a freebie and the game won't take it to account when designing dungeons. Even if they do it's fine as long as we can use it, but there's been a lot of concern that we won't all be able to use it. Whether it's spike teams or non-whales, if somebody gets left out but the game demands they use it things could get ugly. It could just be a metagame shift, which I'm not against, but it could also be a paywall and that would be a very bad thing.
Or it could be a meticulous and well-thought-out design choice to bring more teams up to the high tiers that's explicitly meant to not work with the current top tier and dungeons will not get harder to match. I mean, I don't feel like I've ever been fucked over that badly by PAD, certainly not relative to most other games. The only time I've been really turned off by them was when I got the co-op door kind of slammed in my face, and that wasn't really a design problem. I guess I trust then to not fuck it up too bad, but this is potentially a huge change and definitely a huge unknown. And that, well...
That's frightening.