Lots of discussion, but I haven't yet seen any argument as to WHY gays should be accorded the same rights as married heterosexuals.

On a purely practical level, why should society give special benefits to a living arrangement that does nothing unique to benefit society? Heterosexual marriage uniquely benefits society by providing additional members and by providing the most beneficial environment for those children to be raised to become productive members of society. This is something that deserves protections and benefits.

Any other living arrangement is neutral at best and more commonly, detrimental and subversive.