the obligation to reproduce?
First off, there is at least one other halachic reason for sexual intercourse: pleasure. Men are specifically obligated to provide this pleasure for their wives, in fact. The talmud even specifies frequency requirements! The idea that sex is only for procreation is not a traditional Jewish notion.
If procreation were the only motivating factor, then alongside the familial restrictions (don't lie with your inlaws) and the ever-challenging Lev 18:22, we would see something about not lying with people who are infertile. But we don't, because that is not forbidden. (For that matter, the Torah itself doesn't say anything against masturbation, though I don't know about later sources.)
Some people can't have kids, and for some people it would be a really bad idea to have kids, but we don't chase those people off. [1] We do, however, alienate them every time we say things like "sex is for procreation, and why aren't you doing your part to replenish the Jewish people?". I am especially offended to hear that argument from leaders in the Reform movement -- leaders who are not simultaneously saying things like "Shabbat is central to Judaism and why aren't you observing it?". The sages aren't even in complete agreement on whether "p'ru ur'vu" (be fruitful and multiply) is a commandment; some say it's a blessing instead.
Further, appeals based on achieving replacement levels for population (the number that gets kicked around is 2.1 kids per couple) are misguided on their own. What good does it do to produce more kids, if we aren't also doing something to keep them Jewish? More than half the US marriages involving Jews are intermarriages; those Jews are very unlikely to have Jewish grandkids. And even within Jewish marriages, how many kids continue their education past bar/bat mitzvah? How many kids end up as committed Jewish adults? The problem here isn't production; it's retention. And if we can't solve the retention problem first, then increasing production won't solve a thing. In fact, it'll make things worse, by providing more non-religious nominally-Jewish models for kids who might be waffling on whether to stick with it.
Yes, paying attention to demographic studies is important -- but it is also important not to attribute the wrong reasons to the results. I would much rather have a smaller number of more committed members of the community; nominal body count really doesn't matter much if they're Jews only in DNA.
Growth will come from increasing education and commitment, and from converts. We need not, and should not, pressure people into having more children than they otherwise would have. That is a loss, not a gain, for the community.
I'll probably try to distill this down into a letter to the editor of Reform Judaism, so comments would be very welcome.
[1] Yes, I am aware that the talmud teaches (somewhere;
don't have the cite) that a man may divorce his wife if
they fail to produce a child after ten years of
trying.

no subject
Good point. (I will reread the article I mentioned to make sure that's what this guy is actually doing, though; if he's really advocating that a parent stay home, raising the sexism flag will cause him to blow me off.)
In other words, a man doesn't have to divorce his wife after ten years of trying if he doesn't wish to.
Correct. It's an option, not a requirement.