They got it, they really got it
I have not waded through all 100+ pages of the majority and dissents yet. But back when these cases were in the court I work for, Judge Pollak posed this hypothetical question to me: If the domestic partnership law were amended so that it provided gay couples with ALL (not just almost all) of the rights afforded married heterosexual couples, would it still be a denial of equal protection to reserve the term "marriage" to heterosexual unions? Now mind you, Judge Pollak was and is firmly of the opinion that gay couples should be permitted to wed, but his question was a fair one, and one that needed to be answered.
I babbled somewhat inarticulately about the symbolic power of language. Here is what Chief Justice George had to say on the subject in the majority opinion. It's a little dense, but I think it is worth wading through because it is so very right:
"While retention of the limitation of marriage to opposite-sex couples is not needed to preserve the rights and benefits of opposite-sex couples, the exclusion of same-sex couples from the designation of marriage works a real and appreciable harm upon same-sex couples and their children. As discussed above, because of the long and celebrated history of the term 'marriage' and the widespread understanding that this word describes a family relationship unreservedly sanctioned by the community, the statutory provisions that continue to limit access to this designation exclusively to opposite-sex couples — while providing only a novel, alternative institution for same-sex couples — likely will be viewed as an official statement that the family relationship of same-sex couples is not of comparable stature or equal dignity to the family relationship of opposite-sex couples.
"Furthermore, because of the historic disparagement of gay persons, the retention of a distinction in nomenclature by which the term “marriage” is withheld only from the family relationship of same-sex couples is all the more likely to cause the new parallel institution that has been established for same-sex couples to be considered a mark of second-class citizenship.
"Finally, in addition to the potential harm flowing from the lesser stature that is likely to be afforded to the family relationships of same-sex couples by designating them domestic partnerships, there exists a substantial risk that a judicial decision upholding the differential treatment of opposite-sex and same-sex couples would be understood as validating a more general proposition that our state by now has repudiated: that it is permissible, under the law, for society to treat gay individuals and same-sex couples differently from, and less favorably than, heterosexual individuals and opposite-sex couples."