Champions that have built-in extra turn mechanics as a core part of their kit get screwed over. Seeker basically gets a 50% penalty. Ma'Shalled likewise. Both of those are extremely dependent on those extra turns, but there are of course other examples as well. The extra turn already has advantages and drawbacks over just the regular do-this-then-this skills that are functionally identical minus the extra turn, so penalizing it in this way is just excessive.
Also, whoever set the required turns for the max points was clearly on something really potent. 2 turns in spider is not enough to get even 90% of the max points on 20 normal. I haven't seen 1 turn yet, but I doubt even that will be enough. If that trend holds for the rest of the dungeons, I'd like Plarium to showcase a team for each dungeon that can get the max points, because I have my doubts that it's even possible. Maybe, and this is a stretch, you could do some sort of weird counter-attack one with 0 turns for some of them, but I'll believe it when I see it.