I'm all for reduced sailing speed in the open world all together, I even prefer it to be the same slow (realistic) speed as in battles but I think I'm one of the very few so that would never happen. I really think the game will do so much better with longer travel time, you will see traders work together and Trade ports between great distance, just like in real life. You don't really have to go to the other side of the map imo so it's all up to the player how far he wants to travel, a choice, not a must! But again, this will never happen, to many people don't want that and like it the way it is.