The big difference here seems to be that while the vagina has an obvious functional utility, the clitoris exists entirely for female pleasure. It seems that the issue stems, not from the provocative nature of a word, but our continued societal taboo regarding women daring to enjoy sex. Sure, we can see depictions of women shrieking with pleasure plastered all over any porn site. But that is exactly the point. Female sexual enjoyment remains exclusively in the realm of the forbidden.
Even the stuff about lie back and think of England wasn’t true at the time and it’s most certainly not true now.
Come along now, be serious, any society with 50 shades of white we can apply to the bathroom walls is not trying to hide nor deny female sexual enjoyment.