My boyfriend is a moral objectivist, and we've had some rough arguments about it.
From his point of view, morality is a moot point if it's subjective. He considers the very concept of morality to be a black and white, good and evil, right or wrong system that judges a person's actions as either moral or immoral without regard for context. That morality is almost like an idealistic kind of justice where only facts matter, and that to ignore the facts in favor of emotions or extenuating circumstances is a violation of the entire purpose for a morality in the first place.
For the record, I don't agree. I believe (and was taught in my humanities classes) that morality is influenced more by culture than by any universal kind of right or wrong. That where pedophilia is immoral today, it was totally moral two hundred years ago, or two thousand years ago where you had Greek men sleeping with older boys and it being considered a moral, educational experience. And with samurai. And Chinese nobles... and so forth.
At the same time, there is a degree of objectiveness to morality. Some things are universally wrong by way of them being disruptive to humanity at the most basic, fundamental level.
For example, murder. There's never been a single culture where murder of a fellow citizen/tribesman/clanmember has ever been morally acceptable. Rape has never moral. And so forth. Typically they're things that are extremely traumatic and cause a major impact on a number of peoples' lives. The only time murder has ever been "moral" is in revenge murders (Hamlet and Duncan's son in Macbeth, for instance), but those are only considered moral because the initial act of murder was highly immoral, thus alleviating the revenge murderer of moral repercussions by acting as an agent of moral justice rather than an immoral infringer of morality.
So I think neither objective nor subjective morality is completely right. There's a degree of both. It's all about how you spin the argument. As far as my boyfriend's concerned, subjective morality is too busy with historical apologetics and not focused enough on what is or isn't moral, where I think we have to look at the malleability of morality to understand why we consider things now immoral that weren't immoral before.
And if you were to ask me that question I'd say it's because the Puritans were fucking lunatics. But I digress.