Can we finally stop calling it "gay marriage" and "traditional marriage" and just call it "marriage" now? good job USA I'm glad you are finally catching up to the rest of the developed world.
Yeah, you should start leading again by cross-species marriage too. It may sound bizarre now but that's how same sex marriage was a 100 years back. Marrying your pets should be legal too.
They keyword is consent. Animals can't consent. Children can't consent. Having said that, in a few years (decades?), I could see poly-marriages also getting equal standing under the law.