I'll try to keep this brief...
I get what she did. I get the people who are upset about it. What I don't get, are the people who think it was too small and too distant an incident to fuss over. The people who say nobody is perfect, and everybody has done something they regret, and feel it should therefore be excusable. Why should we hold Deen to a higher standard than the rest of us? Because she's in the public eye. She's in a position to influence our brains and our children and our culture. That's why. Those things you've done that you regret? Odds are, they weren't okay either, but because nobody knows about them (or cares on a society-wide scale), nobody is condemning you to the level they're condemning Deen.
Let's set aside for a moment the fact that I personally think Deen's apologies are more PR than they are sincere. Even if it was an isolated incident that happened in the past and she regrets it, as a society who has now been exposed to a concrete example of this type of behaviour, we can't just let it slide. Because the moment we excuse it in ANY FORM is the moment we let our children believe that under some circumstances, that type of thinking is okay. And it's not. It never was. Even back when it was "acceptable", it wasn't actually fine, it was just a bunch of people who were wrong and didn't know any better. That makes it something we can learn from. But it still doesn't make it okay.
If someone is truly sorry and appears to have a firm understanding as to why what they did was wrong, then I think they should be forgiven. Forgiveness is important. And yes, if Deen really is sorry, we should forgive her. But don't try to minimize what she did. Don't claim it's being blown out of proportion. That's damaging to progress. Your excuses are hindering my ability to raise my daughter in a world where she has no reason to question the fact that prejudice and racism are ridiculous and disgusting.
So please, for the sake of evolution, go ahead and forgive Deen if you believe her apologies, but don't try to rationalize what she did. Or downplay it in any way. It doesn't matter when, or where, or why. It's forgivable, but it's not okay.