> there's a whole internet cult for them, composed mostly of people who don't really live in an area with roundabouts.

Alternatively: it's people who do live in areas which have a lot of them - and well-designed ones at that. Most of your issues boil down to "people aren't familiar with them", which automatically solves itself over time.

There is no such thing as a "roundabout fever", just like there isn't a "traffic light fever". To any halfway-competent engineer, they are just one tool among many.