> When people say something like this, in my experience they will not be satisfied with anything but a high quality, nearly visually identical knockoff of the product that they're used to, and, after complimenting it, they'll find some intangible reason to dismiss the knockoff (at the least, for being "just a knockoff.")

Because the small details actually matter in the experience.

Take Mastodon for example: I can barely see a visual difference after a repost in the icon because the "active" and "inactive" colors are very VERY similar to each other, and there is no change in the number next to the repost icon either. As a result I have to very carefully go near the screen before I repost something, and that makes a pretty annoying experience.

UX/UI in general is the largest issue that FOSS projects have, because the people actually knowing their shit are expensive to hire and the experiments needed to figure out what works better cost serious money if you want to go beyond "run a/b tests and piss the hell out of your users who are unwittingly being used as guinea pigs in a code farm".