Polyamory is more than two people having a personal and sexual relationship, usually living together. Polygamy is one person married to more than one person, which is illegal in most states.

There may be some overlap, but I think polygamy/bigamy would require a larger commitment than an open relationship. Marriage itself as defined by law in most countries is just between two people, and that is all that is really legally "official". Outside of marriage polyamory is just an open relationship.

I think were missing the point we r animals that do things a certain way for a reason how come polys and monos r aloud to corrupt it

It's not polygamy unless they are married, and polyamorous people usually just have multiple lovers, or take casual lovers on the side, with the permission of a regular partner..nothing official.

I think it's to sound more palatable to Christian orientated people.