"Fix" Speed Runs? How about fixing the real issue?

[Jeht]

I think the problem is the mobs grant no incentive and are face rollable. At least the bosses grant a challenge, however small it is.

Face rollable for you. There's a lot of tanks out there that have a lot of problems on trash, let alone mechanics like dodging bad red stuff. Trash still provides a barrier and a learning incentive to players. Especially the few that rerolled tank and skipped lower level dungeons.