Carrying them around for a day in a sealed waterproof bag's not so bad, if you have a diaper bin to dump them in when you get home and a diaper service to take them away and wash them for you. It's just a hassle when you're going back to a hotel room and there's no service and you have to wash them yourself. (Just what I want to be doing after a long hot day at the parks!)
And, as others have pointed out, there are now hybrid options with all the benefits of cloth and the convenience of disposables.
Also, the age of the baby will determine how awful the diapers are. Tiny, completely breastfed infants have pretty inoffensive poos. But the diapers of 18 month olds are downright nasty.