You have to understand that you were sailing on NCL - their motto is, "You're free to.... whatever." So you'll find everyone is alot more casual in their attire for everything.
They don't have any 'formal' nights like most of the mass market cruise lines do. If you like formal nights, then you really need to try some other cruise lines. Depending on your age and lifestyle, you might prefer a little more upscale cruise line. My personal favorite is Celebrity as it's alot nicer with MUCH better food, and is definitely more upscale without being 'stuffy'.