>>39221060My gut says that it started as a bug (Don't forget, this is the gen where a Moon Ball is effective at catching pokemon who evolve when a Burn Heal is used on them) that was elevated to feature. It's possible that they tried to code in some "special" breeding effects for Nidoqueen when bred with a Nidoking, like producing eggs of both Nidorans or something, that accidentally just caused a code brick and sterilized the poor girl.
Either that or they left it as a placeholder to fill in with some cool shit for when you breed a Nidoking and Nidoqueen that they just forgot about.