We still do the tux and formal gown for formal nights. We don't get dressed up too often, so that's fun for us. We also get a great picture and we don't have to get an appointment at a photographer to get it either.
I certainly understand the extra luggage side of this and how it may push more people into not bringing the formal attire. But if we can manage it we will. Except for the Cruise Chat cruise. A 4 day cruise may not be long enough to want to bring the extra luggage. I'll probably do a smart casual night instead and make it through on a single carry on bag!
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007, Celebrity Silhouette 2013