That would be a good idea, but it kind of ruins the thrill in sailing. I mean, if you go searching and all you find are crates, it makes it even more exciting when you actually find a royal chest. If you just keep dumping them, sure, it'll make some more money, but it won't be as fun.

I just hate it when I come back with all cargo crates!! I really just want treasure chests!! ( More Gold ) ;)

i would like to dump stuff. ( POTCO CREW ARE WORKING ON THAT!)

Yes, the test server currently has a feature under review, that will basically swap cargo for the most valuable once your cargo is full. It is automatic, not a choice of those sailing.