-It's different, and cyclists like their rigs to be unique
-We already shave our legs and go out in public in what other people consider underwear, why not go for broke?
-Several component makers are making good pink stuff
Case in point:
-Chris King's Pretty and Strong pink components
-Hope Components pink hydraulic brakes
Photo from http://www.hopetech.com/
I'd sport a pair of those, just to see the looks on people's faces. Flower cutouts in the rotor? Why not.
Speaking of highly individualized bikes, check out James Huang's coverage of the North American Handmade Bike Show. All killer, no filler. Lots of pictures of good stuff.