"Don't be a dick" seems like such a simple rule

So...yes. Gay wedding cakes. Now, here's the thing: this isn't really analogous to refusing to provide gay people essential services. And you could easily say something convincing-sounding like "would you require a Jewish bookstore to stock Protocols of the Elders of Zion?"

But here's the other thing: if someone goes around comparing gay marriage to nazi propaganda, you would be entirely justified in punching them hard in the genitals and shouting WHAT THE HELL IS WRONG WITH YOU?

This isn't a legal argument. Obviously. But I think people often get stuck in this legalistic morass while ignoring the potent moral and emotional points. How do you think someone's going to feel to go into a store to make preparations for what's supposed to be a joyful day and have the clerk go "nope, sorry, I think you're not fully human, so pound sand?" People glibly say "oh, just go somewhere else," but you think that isn't going to be the most awful feeling? Where's your empathy?

People have the right to be cruel, I guess. But let's not countenance the impression that legal=ethical/moral/humane set in. At the very least, I think homophobic bakeries should be required to put big ol' NO HOMOS signs out front. See how the sacred Free Market likes your smallness.