I just wanted to chime in as well, please don't remove the runes past level 40. I've also been sprinting non-stop to try and get the rewards. It's unfortunate that so many players have been complaining about these stretch goals that you put in(and a lot of players have been asking for since season 1), that they are now making you second guess your decision. I'm one of the end game players that thinks they can actually achieve 100, and I'm willing to sacrifice my entire dungeon season running strictly for points and gaining 0 idols to try and accomplish it.
Bipp makes a good point about not removing the runes, so we'll likely just move them earlier down the track and keep it materials-only past a certain level.
I think you could totally make level 100 too, especially with the points missions.