Bezman habayis, tahara status was public info. Will require tremendous cultural adjustment when Moshiach comes.
Your claim that it was public info is open for discussion. Just because she's tamei doesn't mean that the whole neighborhood knew about it! It still could have been discreet as much as it could be.
Secondly when moshiach comes we'll be back to the status of adom harishon kodem hachate, and since niddus is part of chava's punishment, it wont be here when moshiach comes.