I never attached any negative connotation to the term "serial monogamy."
I just thought that that was what I did before I discovered polyamory was an option. Really. I had to have a discovery moment:"OH! I could totally do that, and I think it would be better!"
For me, serial monogamy means instead of having one pair bond for life, like my sister in law who married my brother just out of high school and looks to not be interested in ever pairing off again, I tended to have one monogamous relationship at a time, and would pair up again after that relationship ended. So, there wasn't any connection in my mind with how long or serious the relationship was, it was serial monogamy because whether I dated a guy for 6 months or married him, I only had one pair type relationship at a time.
I happen to like poly better, now, but, I really was unaware of it as an option for me for waaaaayy too long.