are such details necessary ..... but OTOH it really depends on the type of pax/culture etc.. because it can be quite ikky if people don't use it correctly having such additional bidet etc makes it even worst. Just see how having such bidet in toilets in countries like Malaysia are.. it's wet everywhere.
Even with the built in ones in the toilet - sometimes you see the surface with some exciting colours/leftover....

But back to the topic - no, only carriers I have seen such facilities are on Japanese-based carriers. Not sure if Korean Air or EVA has it (the last time I flew China Airlines I did not notice it in J) has it too (just because they do have it quite standard on the ground facilities)

Cheers!