My biggest complaint is not being able to turn my raft. I built a wide rectangular raft to collect stuff and today I ran into an abandoned raft and it turned me. The only way I found to turn myself is to run into another raft or an island.
A Rudder would be a great and simple way to turn your raft if anything happens. I also think moving with a rudder and static sail rather than a turnable sail would be simpler and would make multi sail rafts function better.