You may have had a comparison in automobiles: white cars never look dirty and black cars are always dirty. Same for porcelain. Very difficult to keep that "showroom" shiny look.
This is just my personal opinion, and I have absolutely no taste in decorating matters, but for what it is worth: The fixtures are a long term committment. If you change your mind in 5 years about that black toilet and sink, you either have to live with it or shell our some serious bucks. If you stay with white, you can decorate around that with accents including tile, curtains, towels, rugs, accessories, etc. In this way you can totally change the look at a fraction of the cost of a remodel.