I greatly enjoyed my last two NCL cruises where I never had to wear a tuxedo or dark suit. I still brought a sport coat and slacks for the Le Bistro and Cagney's.
It cuts down on the packing, is more comfortable and for the group I was with it was a more comfortable experience for them. It was also nice to see that NCL enforced their "No Jeans" policy.
I would rather have a good conversation and a good meal rather than worry about the type of lapel, tie, shirt or cummerbund. I do like to dress up but the tuxedo is becoming less appealing for me. A well tailored suit is more appealing for me and the woman I truly want to impress. It also has far more flexibility for the real world.