I think it would be great to be able to go back and run content you already did that lockout (minus any loot). What happens if your FC has more than 8 people show up to kill things? At the moment, 8 people get to play and the others get put on the bench.

It would be nice if those Bench-Warmers could progress too. Instead of being hooped for the week. Maybe SE thinks that if people go back to run friends through content that they will get burnt out more quickly? I don't know, but I think that should be up to the individual player.