I get what you mean. But is there anything wrong with a game having a relatively strict colourscheme?
I'll bet Tony Garcia had something to do with this game… or if he didn't, he probably wishes he did. Because he's responsible for most of the pink things in previous R&C games. But he didn't do Obani Draco, which is funny, because he was told off for using too many pink effects, and then this level came into being. He wasn't all that happy.
Tony was an Insomniac back in the days of R&C1, 2, and 3. I know this stuff because of the Developer Commentaries he does with Mike Stout.
This level will be finished when LBP3 is stable enough to create with.
I guess every color scheme has a purpose… The blue in GC/FFA can suggest something fresh, a new start. The orange in UYA might be inspired from explosions and destruction, or idk. The red in RG simply points out the blood spill and the gore of the arena, even if the game doesn't actually show it. So, the black + purple-ish colors in Nexus might suggest the more darker and serious atmosphere of the game, with the deaths of Cronk and Zephyr and the whole responsibility thing and blah blah blah… Just a silly attempt to explain the color schemes, they might as well mean nothing. By the way, please tell me I'm not the only one annoyed by the fact that all fully upgraded weapons in ItN are golden. For me, their former good looks are ruined!