Well, it would be good news for the pro-lifers who actually want to stop abortions. It wouldn't be very good news for the ones who want to punish women for having sex and couldn't care less about abortions, babies, or children.
They exist.
There is a pronounced tendency among social liberals to assert completely sans evidence that a conservative stance on sexual ethics and morality is due to hatred, bigotry, or in this case some bizarre punishment fantasy. Many social liberals either cannot or will not understand the where social conservatives are coming from, so we get to hear this incredibly self serving narrative about how socons are bad people rather than people who disagree on the basis of ethics.
This obviously isn't true of all pro-lifers or all socons, but the specific case of the rape-and-incest set of exemptions is enough to make me cast something of a cold eye on the motivations of people who support it while still maintaining that life begins at conception. It comes across as disingenuous, because if these are really human lives we're talking about, it makes little sense to make exceptions to their right to be alive on the basis of how they were conceived, whereas if banning abortion is about punishing women for having sex, it makes perfect sense. I've talked to Catholic priests who have said (I can only assume off the record) they'd be willing to live with overall laxer abortion regulations if it was necessary to ensure that the implicit sentiment (or the sentiment that they infer) that lives that begin with rape or incest are inherently worth less after they've begun wasn't enshrined in law.
The rape exception comes mainly out of a sense that banning abortion in case of rape is in one way or another asking too much. What it is implicitly saying is that there are values other than life, and comes out of a reluctance to demand that people fulfill completely unchosen obligations. It accepts the logic of appeals to reproductive choice up to a point, but that if one has chosen to have sex one takes responsibility for any life that arises out of that. The alternative, to say that one has a duty to care for and protect a life one did not in any way choose, is in many ways a counter-cultural position, especially when asked of someone who has been victimized.
