There's a few more of us out here who would party with you and Mono you don't need to be that marginalized. :-).
I think the reality is that even those of us identifying as mono are all slightly different and in a way polyamory has allowed us the freedom to explore and discover those differences. For instance Mono is mono all the way; while you, if I've read correctly would like to add another lover if one showed up. Even I would be open to it if someone who was a perfect fit into our life popped up, although I certainly aren't actively looking and I would be very careful because I'm enjoying this period of calm in my emotional life after the turbulence of adaptation.