I wonder if you’ve fully articulated your beliefs, here, Marc:

I agree that–other than their unique family structure–there is nothing that sets these folks apart from “average” people.

I ask because I think your “however” is insufficiently strong to stand its own ground in the cultural arena:

However, I think that the baseline structure of the parent/guardian relationships that they have cobbled together, which form the foundation for the family they have “designed,” is inherently more complicated and, thus, potentially more confusing and damaging to the children who are supposed to be the most important star(s) of these family constellations.

Already, within the quotation that you provide, one can find the argument that families formed around heterosexual relationships can be equally complicated — perhaps more so, for having not been “designed.” And what if sociologists and psychologists — ever ready to define normalcy into their own intellectual preferences — are able to show that complication is not a detriment to children? I agree with your conclusion, though, so I’d suggest we look for ripples in more fundamental waters.
However complicated they may become, traditional families offer a very compelling narrative for children’s place in the world: They are born through the sexual expression of their parents’ love and act as a bridge from ancestry to progeny. In Christian terms, they are the full fruit of their parents’ spiritual joining in matrimony, binding their parents (and their parents’ families) together in a relationship reminiscent of God’s creation of mankind. In evolutionary terms, they represent the joining of their parents traits in a purposeful development of their species. Anywhere within this range of perspectives, they are a significant end, a significant achievement, in themselves.
Even if they were the product of a “Whoops! We’re pregnant!” conception, children have access to this meaningful construct. Even if the parents separate, the child still has a claim to the romantic, religious, evolutionary context within which he or she was born; it’s the parents who have fallen short. Even if the parents adopt the child, he or she fulfills a role for them that the biological parents were not able to need, just as the adoptive parents fulfill a role of which the biological parents were not capable for the child. Now, I’m not saying that we moderns haven’t dulled the shine of the marriage ring, or that parents’ choices after their children are born do not matter, but in whatever set of terms one chooses, there is an inexpressible truth to this: the genealogical tree is much more than a breeding chart.
With “alternative” families, it’s not so much that the family’s story is more complicated as that it must be made complicated in order to create the illusion of this intangible purpose. Merely from the fact that the parents inherently refuse to acknowledge that their relation to their child is not “normal” — let alone “ideal” — the emphasis changes. Their relationship was never about merging themselves in the person of a child. The surrogate parent — from the start a necessity — was chosen, at best, for “traits that I want for my child” or, at worst, for being “amenable to the lifestyle that I wish to live.”
I can hear the objection, already, that heterosexuals choose spouses for the same collection of reasons, but that only highlights what’s missing: that the relationship chosen for the sake of the children is at least intended to be the most significant relationship in the parents’ lives, in a manifest confirmation of that incalculable meaning.
I do not doubt (especially having just read a New York Times piece so naked in its leveraging of emotional weight) that the majority of homosexual parents will do the best that they are able for their children, nor that any given family will find broad social or metaphysical considerations possible to overcome. However, they are drawing on a pool of cultural capital while insisting that its plain basis be ignored for their sake, and that is “what the big deal” is.