After having my suitcase misplaced on an 8 day Carnival cruise, I absolutely, carry on my suitcase. It was day 5 before we were at a port that had any shopping options as our 1st stop was the private island. The options onboard were limited to: fun ship t-shirts, Billabong booty shorts and a delightful assortment of horrid one piece swim or postage stamp bikinis - both with limited size options. There was not options on board to buy underwear, bras, etc. Fortunately, I made lots of new friends on that trip who kindly shared their extra clothing with me.
I generally pack pretty light with a carry on size piece of luggage and a beach bag so it's not like I am schlepping around some giant suitcase. My suitcase showed back up on the night before debarkation.