In a turn-based, being unable to do anything, is more something of a fun killer, because people tend to get bored and feel restricted. If you are playing single this is hardly an issue, because you play in that case multiple characters and therefor will get to do something every few turns. But if you are playing 4 player coop, it can be a really long while, where people will tend to tab out or do other stuff.
Also it kind of forces you to have a loremaster with high wits, which is more limiting.
