Despite the ultimate goal of sex is reproduction and preservation of the species, it also serves the secondary goal of being a recreational activity and a means to sate the lust/"heat" of the ones involved.
Granted, we're debating whether or not fictional characters and therefore a piece of fiction should or shouldn't have pregnancy involved BUT if we're applying real world logic to such things (as in that being the goal of sex), then it's not out of line applying the other point of view as well. We could discuss the hassle of having children but then we would be getting into territory that I don't really want to touch in a porn game forum