I think that when peopoe go on a cruise ship vacation, they want a completely different environment than they have at honem (other than modern conveniences, of coourse! So the ship designers use colors, fabrics, themes, etc. to create a unique world unto itself.
I have only bee on Sensation so far and really don't like all that neon, purple, orange, etc. as I just didn't find it "fun." I'm glad Imagination has more subdued colors as I'm more into "relaxation" than "fun" so I will enoy sailing her in just over 5 weeks!!!
Looking at the photos I've seen of other ships, they all have a "take me away" feeling that let's the cruise know they aren't in Kansas (or Chicago, or whereever home is) anymore and that is part of the excitement of going on vacation. Most hotel rooms are dull and boring, and cruise ships definitely are not!
I also love architecture and design and art, so from a photographer's point of view, it's fun to look at all of these aspects of cruise ships.
Too much of anything, like the urns mentioned in an earlier post, I agree, is just too much.