But men, vasectomies or not, are not allowed to marry other men.
The fundamental purpose of marriage is a male-female union, for only a male-female union can procreate and rear children. The fact that many male-female unions do not or cannot procreate does not render this fundamental complementary biological union irrelevant (although such sterile unions have diluted it).
There is enormous value to society, and to the men and women involved, in male-female unions that do procreate and remain faithful to provide a stable environment for children to flourish and to learn from example how to perpetuate that good through their own marriages and children.
All other human relationships fall far short of this ideal--which is a fully achieveable ideal.
Alost all of what gay activists are seeking is already available (e.g., hospitals allow visits from friends) or can be provided by private agreement. One way to view a "civil union" is to view it as a special form of business partnership that extends to the domestic realm. But if such partnerships are allowed, there is no practical way to limit them to male-male or female-female relationships. Neither can they be limited on the assumption that the partners will or desire to engage in intimate sexual behavior with one another. As a practial matter, any person (of legal age) would be allowed to enter such a partnership with any other person.
Gay activists are not happy with that. They desperately desire the approbation of society. They want the to be lied to and told they are what they can never be: the moral, legal, and biological equivalent of a male-female union.
I hate to disagree with you, Kevin, since I usually do agree with your comments. From everything I have read (and I shamefully admit I haven't read EVERYTHING scripter has) the homosexuals you describe are the useful idiot ones. The real activists (like Michaelangelo Signorile) have admitted that their real reason for demanding marriage is to destroy it as a cultural institution, and this will enable them to fully indoctrinate children in the values of hoomosexuality right from the beginning. This is Signorile's admitted statement, as well as the platform of other activists.