Well, obviously, there are a number of people who never dress up because their jobs don't call for it - and many of the guys (especially) don't feel comfortable doing it because it is unfamiliar to them
Then there are the men who dress up every day to go to work - and they just say "I'm on vacation, and I don't want to dress up on vacation."
And at the other end you have people who DO like to dress up, and many of those people go on cruises largely because it allows them to get dressed up, which they would hardly ever do otherwise.
I truly cannot say I enjoy getting dressed up. Once I'm done getting dressed I generally don't mind it, but the prospect of havung to get all gussied up generally does not thrill me.
But then again, half the time I am on a short media cruise and they generally give about 10 minutes to get ready - and that is not too much fun.
If I had an unlimited budget and a body like Matthew McConnahay I would probably enjoy buying formal clothes and looking good, but I don't and I don't.
Back in my Royal Viking Days I had a few different suits and I enjoyed doing the formal thing - matching kerchiefs, argyle socks - I was a regular GQ model, but that was 50 lbs. ago.