Why does it not deserve the same respect and consideration?<quoted text>
No, it's YOUR opinion. You don't give any reasons WHY you think polygamy deserves the same respect and consideration. You just think whatever bullshit comes out of your mouth is valid because YOU said it.
1. Well grounded; just: a valid objection.
2. Producing the desired results; efficacious: valid methods.
3. Having legal force; effective or binding: a valid title.
a. Containing premises from which the conclusion may logically be derived: a valid argument.
b. Correctly inferred or deduced from a premise: a valid conclusion.
It deserves the same respect and consideration because it is marriage, just like same sex marriage no better, no worse. Equal. It has been around way longer that same sex marriage and it is more common throughout history than same sex marriage.
And most of all it deserves respect and consideration for the EXACT SAME REASONS same sex marriage deserves respect and consideration.
Why are you a hypocrite?