Well, its definetly more elegant then toast and cereal at home. Or even breakfast at Denny's. I find after sightseeing and shows at night etc. it's hard for me to get to the dining room for breakfast. I think I've done it once. But you should try it at least once and see if it's what you expected. Maybe it's something you'll enjoy more then the rest of us. That's the great thing about cruising. Everyone has different things they enjoy. I would NEVER miss the evening meal in the dining room, yet I've read reviews where people never get their as they do lots of sightseeing and would prefer to get something at the buffet, plus they have no desire to get out of the swimming clothes.
First morning of your cruise, YES you should go to the dining room and have your mimosa and see if that's something you want to add to your iternary every day.