Removing the capability to lowman the 8man dungeon means you need to keep enough active members in your shell to always have 8 on when you want to go. What's the problem with that, you ask? It means more often than not more than 8 people will be on and wanting to go and you'll have to make people sit out. Telling people to sit on the bench wasn't fun in WoW and it won't be fun in FF14.