Don't remove the ability to dictate if a person wants in progress or not. Believe it or not, some people actually want to do a run from the very beginning to get as much EXP as possible or have a shot at certain loot that only drop from the first or second boss. I used in progress for a WP Hard run today and I was dumped into a party stuck on the final boss because their last healer raged quit. They practically thanked me for helping them out and I managed to get the robe I was hunting for. I actually like helping people recover from a healer who ditched them. Don't remove the join in progress option.