My original point was that while in many places continence and celibacy are encouraged, in the English speaking Buddhist world they are not generally mentioned let alone discussed.
it's an interesting question. The English speaking Buddhist world can be pretty heterogeneous so it's hard to point to one reason, rather than multiple reasons, and a part of it is generational as you've previously pointed out.
One way to look at it might be to see what role Buddhism itself plays in the English speaking/Western world. Religion, including Buddhism, serves a couple of roles within a society. One role would be to serve the spiritual needs of the individual. Another role would be to provide a pathway to achieving the spiritual goal of the religion (enlightenment, oneness with God, etc.). Religion also serves as a the moral and ethical backbone/authority of a society. In English speaking countries, the Christian Church has been the primary religion, especially as it comes to the everyday moral/ethical behaviors of the community. Within the churches, continence and celibacy are hugely encouraged and that permeates the fabric of the society. In the US, while we may look to Hollywood as the norm, for vast swaths of the country, Hollywood is looked at as the "other", especially within the institutions of the different churches.
Getting back to Buddhism, Buddhism is a foreign religion that has no societal responsibility to set the ethical and moral standards for the society ( this is different than saying Buddhism doesn't encourage these as much, or even more, than Christianity, Islam, etc.). That is, in the United States, or Canada, or England, the leaders and the populations of those countries aren't going to turn towards Buddhism to define what moral behavior is for the country. They turn to the Bible, to the teachings of Jesus, or the Old Testament.
This allows Buddhism in English speaking countries to focus on the spiritual needs and development of the members of their sanghas. We can then also look at the people from English speaking countries (or the West) and why they might be attracted to a foreign religion, one that most have not been enculturated to. The question is, what needs do they have that their own country's religion aren't meeting? Also, many are actively turned off by many elements of their culture's religion. Specifically when it comes to sex and morality, Christianity (and I use Christianity loosely here to stand in for the different sects and Islam, Judism, etc) can be seen as hypocritical and far less forgiving of the transgressions of sexual propriety over far more significant moral failings. An extreme example would be that it's far worse for a kid to masturbate than to join the military and go kill people in the Middle East. Or it's okay for us to invade countries and kill hundreds of thousands of civilians, but it's immoral if soldiers in the army are homosexual.
I think many people coming to Buddhism in English speaking countries don't want or need Buddhism to teach them morality or to preach to them a message that sounds familiar to them from their Christian upbringing. Even if you don't have a Christian upbringing, you are still exposed to it and confined by the teaches by the society at large.
I think the equation of lust = desire = suffering does come across, to an extent, as the moralistic teachings of Christianity. Just by framing the discussion of lust as sex serves this purpose. There are lots of different types of lust. Lust for power, for wealth, for fame, for an easy life. Apple releases a new iPhone and the lines stretch out the door and down the road for a quarter mile. Talk about desire.
It always fascinates me that celibate people (for instance the Dalai Lama, or Catholic priests, etc.) think that sex is an overriding end all and be all for people that are not celibate, or that sexual desires and wants supersede all other forms of desire, or that relationships just lead to suffering, more that just being stuck in Samsara leads to suffering. There are studies that show that married men live longer and healthier lives. There are many positive benefits to relationships. I look at my single friends and my married friends and on the whole, my unmarried friends appear less happy. I know that many of my single friends are not out having sex, and in some ways, have backed into celibacy. I also know, to an extent, that my married friends (married people in general) are not just devoting their lives to sex. In some ways, being married and having a source of sexual companionship reduces the need for sex. A thirsty person thinks of water. A hungry person thinks of food. A person with no sexual outlet thinks of sex. I recall that for someone to practice certain forms of mysticism (such as Kabbalah) he needed to be married and older, the idea being that a certain psychological stability was required for the practice.
Perhaps continence and celibacy isn't a main focus for those in English speaking country, because there are lots of other issues they need to deal with to progress on the path - and focus on sexuality wouldn't be a skillful means. I'd be curious what the large Buddhist sects are in the English speaking world? Zen? Tibetan Buddhism? There's probably also a difference between those sects that primarily serve ethnic communities (that came to Western speaking countries with immigrants) and those that serve native born English speakers. It would be interesting to know if there is a difference in how much discussion of continence and celibacy is done between Buddhist Sanghas that deal with the ethnic communities vs. those that are primarily outside of the ethnic communities.