This can easily be put to rest.
IF you are going on vacation to these countries for a week (non-cruise), you need the shots.
IF you are going on a cruise ship, you do not need the shots. HOWEVER, you are taking your own health into your own hands. These diseases run wild down there because these are 3rd world countries & the governments (or lack thereof) do nothing to contain anything.
IF you are going on excursions that will take you into the jungles or anyplace where the mosquitos might get you, get the shots. Yes, it'll be annoying.
But the alternate is worse - say you get one of those diseases - you infect the ship (if it can spread) & the cruise line has to make an emergency call to get you off the ship & back to the States for treatment. This probably won't be covered unless you buy some sort of insurance.
If you are only staying in the port area, you should be fine. Just watch for the mosquitos especially after it rains. Buggers up here in CT love to come out & suck you dry after a good rainstorm.