TexasGator, God's plan is that fertility is time-limited and periodic. If you conduct yourself as commanded in the Books of Moses, you'll abstain from Day 1 of the wife's menstrual cycle until 7 days after the last show of blood --- therefore about 12-13 days every month --- which sees you resuming marital relations just a day or two before ovulation, in a typical cycle. This also happens to be when the male finds the female most compellingly attractice, and female pleasure doo-dads are most receptive, woo-woo. Therefore Torah-based intercourse is optimally timed for making the Song of Songs really sing (!) and for conception.
Natural Family Planning -- observing and honoring the fertility signs, and regulating your behavior accordingly --- can be used either for avoiding or achieving conception. Thank God for this excellent design.
On the other hand, even intercourse when no conception is possible, is still related to the reproductive purpose of marriage, in that it can establish-maintain-strengthen a basic pleasure bond between husband and wife. Thus it tends to keep the pair together, which eliminates promiscuity, which eliminates the transmission of devastating sexually-transmitted diseases, which stabilizes the wider community overall, which is necessary for the durability of the family unit, which is essential to the proper raising of children.
So you've got pleasure at the service of both procreation and lasting couple satisfaction.
To which I say: Yay.
Sex also emotionally bonds men and women, more so with women it seems, but it strengthens the marriage when experienced regularly.