At least the standard 918 wheel bears less of a resemblance to a certain male body part than the McLaren base wheel.
Dave has a point about the caliper color being a signature of the tech theme. I guess the same could be said of the base wheel too. Many of the hybrid cars seem to have very complex wheel designs. Honestly, you could put wooden wagon wheels on the 918 and it would still be fantastic.
FWIW - I like the looks of the stock wheels. They told me the can change the caliper color without much difficulty. Perhaps lots of folks don't love the green. You can also have most of the badging removed, which I found a bit intrusive on the aesthetics.