The rank system is a blast and has been a huge hit across the board with everyone. I really can't think of anyone who's come out and said they don't like it, and it ties in very well to development... especially development in a slightly different direction from canon, as you can have your character plunked into a role they contrast with and must learn to adapt to (i.e. imagine having a villain rank up as a King, a supportive healing role). There is a lot of room to tell a personal story based on how the game is set up, and plenty to achieve, such as pursuing a house or a business, which adds to the appeal.

As for antagonists, there's actually a great niche waiting to be filled for that! The premise of the game is set up in such a way that a clever character could manipulate public opinion behind the scenes. Not every character is on board with playing Hero just because they're told to, and there have been some suspicious things implied about the great powers behind it all. We have a wanted system in play for characters wanting to go rogue that could potentially be a lot of fun in numbers. All in all, villainous angles haven't been explored in-depth yet by any of our current roster (if anything we could stand to have a few more bad guys), but the potential is there and I could see a lot of people going for it. You can read up on the punishments system surrounding this here.