The vinaya was traditionally not taught to those outside the bhiksu(ni) community. There was a fear that people would use those precepts against the community.Aemilius wrote: I have often wondered what kind of karma one acquires when one so eagerly discusses the points of vinaya and at the same time one is never going to commit oneself to following it even in the slightest!? I'm not claiming that I have never done it myself, but I would like to be careful about that, karma is easily created and it will last for milennia, I also feel a certain heaviness in this topic.
There is a good reason behind this policy that monks must get married, the answer lies in the history, maybe they don't like to tell that kind of unpleasant and nasty things anymore? I.e. the causes that led to this new and I would say healthy practice (of monks having to marry).
But times have changed. Things are more transparent then they used to be.
Your fear of karmic retribution is wise, but in this case there is no intention to harm others, but rather to foster a healthy community and proper training and certification methods.
In the case of Korea and Japan, there were numerous factors at work. The first is that when the vinaya tradition died out there was no actual mechanism in place to forbid marriage. In such a scenario you might have traditions forbidding marriage of tradition and doctrine, but no actual legal mechanism exists in place to prevent it. In the case of Japanese sects it started with Saicho when he decided that he would ordain "Bodhisattva monks" without the Vinaya, having concluded the Sravakayana-vinaya was unsuitable and unnecessary for superior Bodhisattva practices. Legally monks in Japan were forbidden to marry until the Meiji period, but then things rapidly changed under government influence and this hereditary system of temple ownership development passing from master to disciple or father to son.
This system was pushed on the Taiwanese Buddhists, but they actively resisted.
It was some success in Korea.
I can't speak for Korean Buddhism as I have no experience with it, but in Japan being a priest for the most part is a hereditary position you inherit from your father for the purpose of maintaining both the temple and the graves of the local community where it is situated. Whether you really give a damn or not about Buddhism isn't really an issue -- it is a family duty that is required to be filled. Nothing more.