Our diocese is currently considering making an NFP course a requirement of marriage preparation. If the diocese changed their requirement, all couples would be required to complete a full course in NFP, which generally means a series of three classes and charting follow up. Currently there is required NFP training, although it it generally mentioned briefly in the general marriage prep classes, or brought up by a priest when individually counseling couples. I have mixed feelings about this. We were not required to learn NFP while engaged, but we took our course at a parish that requires it, so we've seen a little of both situations.
On one hand, I really like the idea of requiring NFP training before marriage. Natural Family Planning is really just information - it's helpful to any couple of childbearing age. There's an obvious utility to requiring this course for couples who plan on postponing children when they are first married, but I think it's also useful in other cases. If a couple plans to try to conceive as soon as they're married, NFP can help them identify any obvious fertility problems when they are engaged, giving them a head start on addressing those problems. A well-rounded NFP course also covers how to increase your chances of conceiving, the benefits of breastfeeding to mother and child, and breastfeeding's effect on fertility. If these couples wish to use NFP after the birth of children, they will be able to pick it up much faster than if they had never charted before. This is especially important because post-partum charting can be more difficult, and of course, time is precious when a couple has small children! Finally, many couples switch to trying to postpone pregnancy during very stressful times in life - job loss, financial troubles, health problems, a child who needs extra help - and it's good to already know the basics of NFP before hand, so you aren't trying to learn something new and difficult in the midst of everything else.
I think Natural Family Planning also encourages a healthy attitude towards married life and the "marital embrace." While it encourages generosity in having children, it also encourages sacrifice for the sake of your spouse and family. Yes, abstinence isn't fun, especially when it's lengthy, but it also isn't difficult when the health and well being of your family is at stake.While I don't think NFP is required by Catholicism (after all, for most of history Catholics haven't used anything other than abstinence to space children!), I don't think learning NFP makes us less reverent - in fact I think it really highlights how amazing marriage, sex, and children are! Good NFP courses discuss the theology and moral aspects of married sex and parenting - these parts are relevant to all couples and they're not really about charting.
Having said all of that, our classroom experience of NFP wasn't great. There were about 10 couples there, and I'm pretty sure that there was only one other couple that wasn't already having contracepted pre-marital sex. This shifted the tone of the class dramatically. In a class where most couples are already having pre-marital sex, post-marital abstinence is a difficult sell. It was difficult to talk about charting in a practical manner because most of our classmates weren't interested in learning to chart because they were already using hormonal contraceptives. And our teaching couple's attention was focused on 8 couples who weren't happy to be there, instead of on the 2 couples that actually planned on using NFP.
Now, I suspect that a great teaching couple might be able to handle this type of classroom. They'd be able to gently persuade the reluctant couples of the wisdom of NFP, teach couples already intending to use NFP how to chart and determine fertility, and support couples using NFP to postpone or achieve pregnancy, all while being kind, gracious, and inoffensive. But not all teaching couples are saints and they shouldn't have to be. Frankly, if Catholic couples planning on a Catholic wedding are having pre-marital sex while using contraception, something went wrong a long time ago in the formation process! I suspect that the move to require NFP courses for engaged couples is an attempt to handle these issues. I worry that requiring NFP classes for all engaged couples is really just a way to move the blame. Now, we can ask why NFP classes are so ineffective at reaching their audience, instead of why either (a) good Catholic couples weren't taught what the Church teaches about marriage, sex, and children well before marriage or (b) why people who aren't practicing Catholics think that they can get married in the Church without being Catholic.
I think NFP is a very important tool in a Catholic marriage - I think it encourages spouses to be thoughtful about the responsibilities they have to each other and their family, while also seeing children as a great gift. I think that most engaged Catholic couples would benefit enormously from taking an NFP course. But I worry that by mandating courses, we would inadvertently change the focus of the course from giving already-convinced Catholic couples a tool for married life to a sort of remedial "teachings of the Church" class. That seems like a bad outcome for everyone.