One can argue either way. However, from my perspective here in Alaska as well as a 26 year world cruiser, it is my opinion that cruising is a plus for both. Certainly there are some negatives for society that cruising brings but the net impact is positive.
Take for instance the Nation's largest National Forest in Southeast Alaska, the Tongass. For many years loggers and other developers have politically pressed to clear cut and pave over huge expanses of this forest where the Sitka Spruce dominates, a valuable saw log tree that reaches its maximum life at around 800 years, loggers are actually subsidized by the US government to cut these trees, which are then transported overseas with no value added, all at a loss to US taxpayers. Many didn't appreciate or recognize the real value of this standing forest until the cruise industry began bringing visitors to Alaska who made it clear that the unfettered aesthetics and magnificence of it all were worth a lot more to the nation's economy and that of Alaska than any denuded landscape would ever be. Not to mention the negative impact that such deforestation has on a valuable renewable resource there, the five species of Pacific Salmon.
Mass transport, which cruising actually is, is a lot more economical for travelers let alone lessoning the negative impact upon local ecologies as opposed to individuals going it alone burning more energy and creating more waste per visitor.
Case in point, in Seward the other day, a poor mountain goat found himself in the middle of the town. He went out onto the rocks of breakwater trying to escape those attempting to take pictures and following him. After trying to swim for a refuge but unable to climb back onto the rocks as the sight seers were all around allowing no avenue of escape, he drowned. Now, perhaps a cruise crowd would have been guilty of the same, but I doubt it since they are usually accompanied by responsible guides who would have brains and have pointed out the poor goat's plight.