I really feel like, when playing a coop game and a teammate dies, respawning should occur at the next checkpoint, not just during the next lull in combat. It kind of makes sense, but then again, it’ll be a relatively big change in the way co-op has been played for the last 10 years (one person charges in, one person hangs back as the human spawnpoint 
Maybe a skull for this effect? Something a little like Iron Skull, but doesn’t make you restart at last checkpoint. It’d encourage tighter teamwork in the campaign without having to restart all the time when one person dies. It could also make a good Commendation (like Close Call, but rather for being the last player alive by the next checkpoint). I dunno, anyone else this is worth considering?