Important? Yes. Urgent to fix? No, since players can keep track of the number of disorganised units in a sea area and act accordingly by not selecting the sea area for combat. Bugs which cannot be avoided by players are more important to fix, IMHO.
I agree fatal bug are the most important but I disagree that this one is easy to get around, maybe in the beginnig but from middle to late game it´s a nightmare remeber what units are used or not. I´m not a developer but I got a feeling that this one is not a very dificult bug to fix and will make our lives like game players happier. [;)]
Sorry, for my bad english! "Wiffing" since 1990 to the tomb!