It’s all well and good limiting the roster for a given PVE event, but would it not make sense to have a couple of the nodes have covers for the playable characters as prizes? Even if it was just the one-time-only introductory node, with a chance to drop one of four, it would still help people who haven’t obtained many covers for these characters.
This used to kind of be the case. You could still see it in the Red Iso-8 board, where the first board paid off in cap covers. The first or second time they ran it, there was also a node that had purple Spidey as a prize.
More profitable to just expect players to buy cover packs.
I didn’t get either of the purple spidys 
I didn’t either. I think my wife nabbed one, but I’m sure I walked away with 100 ISO-8 or something.