As a relatively new member, I don't mind if old issues are re-discussed on this Forum. It may be old hat to you guys, it's all new to me. And new members may have new perspectives to add.
I am also a linguist, not just a PolyLinguist. I spend a lot of time thinking about words and what they mean. In my view, it is highly useful to have words like "Primary" and "Secondary". They refer to real-life roles - roles that I have seen enacted by real people. Giving another name to these concepts, just because they may sound troublesome to some people, would not serve a useful purpose. Once the new terms gained acceptance, their meaning would start to bother those who were bothered the first time around.
Saying that all relationships are unique, or that we should all love our various poly-amours equally, is not very useful. People can't go through life constantly explaining and defining situations anew as if similar situations have never existed before. The kind of polyamory I can envision for myself has existed in human societies from time immemorial, under one word or another. I would like a lover who won't destroy my marriage - it's that simple (and good luck to me...). In parallel, I may become the lover of a woman without destroying her marriage. If the operative word is a "secondary", so be it. I see nothing insulting or derogatory about it, for myself or anyone else.
The fact is, it is easy for people without strong attachments to dismiss hierarchies. But some of us have strong attachments - it's just that sexual fidelity is not an absolute requirement for them. As long as I am open about this, no-one can be surprised if they sign up to being a "secondary" (call it whatever you want), and they end up sometimes in a secondary role. Yes, my dear, I love you dearly, but I have a household to run, (grown-up) children to spend time with and shared holidays with my wife. If this is the kind of thing you want for yourself, maybe you should find a primary of your own...