Aren't poly relationships a lot more complicated than monogamous ones though?
It depends on the culture. In the U.S. it's not common practice, so I think it's more difficult because of societal standards. I recently watched a TEDx and the presenter had been studying polyandry relationships in the District of Humla. It's more common for women to take on multiple partners in marriage than a monogamous one. It's practical, and more financially stable for families. There were other example from other areas, but this one stood out. The overall census was that it worked well and most preferred it. Again, that's what they're accustomed to.
To add to my previous comment, I don't want either relationship. I stated exclusive because that's how I perceive relationships at a default because of growing up in a culture that endorses monogamy. I didn't mean to imply that I preferred a poly relationship. I can hardly live with myself, let alone having other people endure me.