[...] I have no issue with making in-game purchases available if it has no effect on gameplay.
Many people are like us.
I would say that I'm rather tight when it comes to buy any software, games included.
But when the game is really free, with hours of entertainment and good support, I'm happy to buy those silly cosmetic stuff for fun and to support its development.
I paid Path Of Exile some $35 the month I started to play. I think I've never spent that much for a game !
I've read that I lot of people do so. When those purchases are rendered in game as cosmetics we see the support of the players for the game, that's nice.
I believe that I could be the future for a substantial fraction of the games, but not all of them.
[...] labeling a subsection of microtransactions unethical [...] may be annoying, and insulting[...]
Yes, that's right.
I've just used the same wording as advertised, I understand it may be unfair.
However I really don't like a situation where I'm lured into something labeled "free" and once there I realize that nothing really cool will happen without paying for a few things.
Saying "I don't like" is an understatement, I won't describe the feeling.