In Judaism, I think you will find that the more holy or important that a thing is, the more it is hidden or restricted. The Torah scroll is covered by a cloth, then placed in the ark that has at least two coverings (eg. a curtain and a door). In the Temple, the deeper in, the more one was restricted from entering and the more barriers, doors and curtains one must pass. The kabbalistic tradition, is almost completely hidden from the public with only the most topical or cryptic texts available to those not initiated into it.
Intercourse is, I would say, the entire basis of Judaism. Practically everything we do can be traced back to the concept of the relationship between masculine and feminine archetypes. That being so, sex as the most physically expressed form of this intercourse is likewise understood to be the holiest and most important of our endeavors. As a physical parallel to all our religious services, it and anything related to it consequently needs to be carried out with a certain degree of restriction or reverence.
Practically, that means we need to dress modestly and perform the act under some restrictions. We don't expose our children to nudity or sexual conduct until they're mentally mature enough to approach the subject with some reverence. Nor do we expose ourselves to nudity or sexual conduct that is not performed with an adequate degree of reverence and holiness, so as not to diminish the sanctity or animalize the act in our minds.
At the same time, so long as the framework is adequate, we are exposed to the subject. There's an entire tractate on the Laws of menstruating women which requires some degree of familiarity or knowledge of the female body. Sexual intimacy is not an uncommon topic in the Talmud. In the most religious of circles, ritual bathing is public - albeit segregated - as we don't believe there us something inherently shameful about the human body. As a more extreme example of exposure to sexual conduct in the correct framework not being prohibited, the Talmud records a student (himself to later become an important rabbi) having hid under his Rabbi's bed in order to learn from him ideal conduct. When his Rabbi caught him, and told him "this is not the [correct] way", the student's reply was that thus conduct is part of Torah and he is obligated to learn this too. The Talmud doesn't record a retort from the Rabbi, indicating the student was in the right.
To quote some book whose name I can't recall, the pleasure of intercourse is like the free cookie the bakery gives the kid to encourage him to get his parents to come to the store. When we conquer our animalistic drive, that's the most ideal time to engage in intercourse, not abstain from it. Only for that person is the most sacred act removed from any of the debasement of the world and able to cause the greatest possible effects. And for the rest of us who have not yet reached that level, we do the best that we can, because ultimately, intercourse is too spiritually important to abstain from.
