tbh I think the way some goys see “goy” is less of a “hard J” thing than it is a “I don’t have an accent” “can’t stand to be called gringo / cracker / cis” thing. a lot of the people being fragile about this wouldn’t even say “jew” if they wanted to call us a slur, they would say “zionist”.
but it’s not about the word, it’s about the idea that what they are can even be named in opposition to something else.
they’re normal; they’re the default. they don’t want to be reminded that theirs is not the objective gaze of reality, and that minorities would even have a category that amounts to “not us”
I think a significant dimension to this is the difference between an identifier and an identity, which are external and internal respectively. When I call myself a Jew, it's an identity. It's something I understand about myself, something that's a part of me, that makes me who I am. That's not something that can ever be taken away, nor is it something that can ever be given. Identity is the subject. When I call someone a goy, it's an identifier. It's something I (and other Jews) use to understand them, and how we relate to each other. It can be given, but it needn't be taken. An identifier is the object
Identities and Identifiers can overlap, but they can also be distinct. I am often identified as white, but I don't have a white identity. Most people don't think of themselves as goyim. Jews are a microscopic proportion of the global population, so to the vast majority identifying as goyim makes as much sense as identifying as a non-redhead. (Those who actively identify as goyim are generally turbo racist.) The identity isn't there, so when the identifier is applied it's jarring, dysphoric. They're suddenly forced to confront the fact that people see them in a way that they don't see themselves
This is especially troubling for progressives, who often take the perspective that the few are oppressed by the many (which is frequently true, although the worst among them erase the contextuality of who is considered what). Not only do they not identify as goyim, they don't identify as our oppressors. They think they understand the shape of their world until they're suddenly made to think in a new dimension. In progressive politics, "goy" is seen as flattening the dynamics between distinct, "real" groups of people who have their own relationships beyond what the Jews think of them. In a multipolar world, Jews are accused of creating a new axis to further complicate things, unfairly forcing our perspective on everyone else. And isn't forcing something on people its own form of oppression?
In a world in which universalism is the goal, "goy" is a form of particularism that resists attempts to eliminate it. "Goy" is Jews forcing ourselves apart from people who want us to all be one race: the human race. It's a reminder that not only are we not like them, but that we're not especially interested in it either. I've never felt left out for not celebrating Christmas. I've never salivated over the latest deep-fried bacon-wrapped cheeseburger. Goyim may not want to be goyim, but Jews don't want to be goyim either, and a lot of people resent that (on the left and especially on the religious right)
choosing to "other" (whether yourself or someone else) = internal, self-perceived as empowering
being designated as "other" by someone else = external, self-perceived as a denigration or attack.
Another reminder that human psychology is complicated af yet simple as hell at the same time.
