oh dear here we go again with the cruise wear debate. Its really quite simple actually, a cruise is one of the few vacations where you know in advance that there is a dress code, and that as a guest of the ship you are expected to abide by those guidelines yes the cruise lines have become very very flexible in the past few years when it comes to the dress code, but it is still expected in the main venues. I totally agree with Trip, if you were on a land vacation and you decided that you wanted to have dinner in a really nice restaurant, would you not dress accordingly?? same applies to a cruise ship.
If you really want to cruise you have the choice of a line that is totally casual or you can simply opt out of the formal venues