Firstly; you have a lot of good points. XD
Secondly; I am a woman, and I do agree to an extent that since women choose that its deteriorated a bit, BUT I do not believe that is the soul reason.
In arranged marriages commonly they were arranged to people who could pay or "donate" the most to the family, the family would benefit an amount OR the womans parents had to have a dowry and so it all came down to what it is now adays -- money, wealth, not intellect and brawn (which is part of it), part of the natural way of life is a little bit intellect, and a little bit strength. Being a "nerd" is technically considered a bad gene, you have to have an appropriate mix of both (so being a nerd is too much of one good gene, and not enough of another, does that make sense? As is the opposite being a jock is too much of a good thing, and not enough intellect). Going back to our natural roots we are built to live in the word without houses, cars, etc.
So a "perfect male" would be the man who could hunt, he was swift, he was strong, he could think well enough to use tools to catch his prey etc.
A perfect woman was obviously slender, this represented an agility as men have a tendency to "Fight" and women is more "flight". Not a bad thing, an example of this is if a family has a child and that child becomes endangered for some reason, the male would have the instinct to go out and hunt down the thing that endangered his child, as the woman has the instinct to stay with the child and protect him, thus working together perfectly. A woman also would be a bit of a thinker, as they would have to forage etc.
So really, money has always been an issue and is the thing that makes "Dominant" males now adays, it's not really the men who can work hard and earn their meals, its the men who can purchase the biggest tvs, the most shoes, etc. And in the case of arranged marriages, the man with the biggest pig took the woman.
So you see to an extent I agree but to another I think its simply human greed that deteriorates our kind. I unfortunately have a hard time staying thin, as both my parents have a chubby gene so it kind of comes naturally, but to balance that out (as any woman who followed their basic instincts would tell them) I have gotten with a man who has a higher metabolism than me, and to try to counter my parents if I stay fit, active, and eat healthy when I am pregnant then studies show that there is a way to "turn off" certain genes, or to lessen the chances of them having those genes (I.E. How eating fish helps stimulate their brain.)
We've lost our basic instincts and thats our issue imho, three cheers for an apocalypse! Lol.