...it's about acceptance.
With the passing of Prop. 8 homosexuals couples in California will not be denied any rights that they currently have- homosexual couples will have the same rights as heterosexual couples.
So why do homosexual couples care whether or not they are in a civil union or in a 'marriage' if their rights do not change either way?
Because it's not about equality- it's about moral approval.
Don't believe me- this come straight from the horse's mouth:
Why Moral Approval Matters- 365GAY.COM