Trouble with the "nice" jeans routine is people push that button to the max these days, which is very evident in business casual office attire, using Abbott Labs as an example.
I think dress codes should stay as they are but be enforced by the cruise lines. I don't really care what other people do but always wonder why people change clothes after dinner when it says suggested dress for the evening.
I don't think dressing nice for dinner is difficult, I rather enjoy it myself. I know people love their jeans and casual to them means jeans! :-)
I wear jeans but never when I'm traveling, that's just me. I don't wear jeans out to dinner at home either. If I'm going out to eat at a place that has several courses, nice linens/table settings, I don't wear jeans.