Identities, for me, are not permanent. Well, not all of them, anyway. I allow for plenty of fluidity and lots of possibility for change in my life, so when I say I am monoamorous, I generally mean "have been up to this point in my life."
Once or twice a year I let my mind wander and imagine what it would be like to have another romantic relationship in addition to the amazing one I'm already in.
All relationships are a gamble. Poly. Mono. Something in between. Something on another spectrum entirely. There's no guarantee that it will work indefinitely. You can only succeed if you try, but even then...it's not guaranteed.
...the bottom line is - we don't hate the concept of polyamory. We just don't wanna be poly ourselves.