Bluesky

Full disclosure: I'm trained as a traffic engineer, but I'm a disgruntled/disillusioned one (and a mod of !fuckcars), so that should give you some indication that my answers will be informed, but very much not unbiased.

Is there ever a traffic setting where this can be considered good?

The main thing to understand is that this design exists to mitigate the problems associated with a gigantic stroad, so strictly speaking, no, it's never good because stroads are never good.

That sure makes it sound like a situation for an over/underpass with simple ramps for the major road / highway.

Your intuition is correct! By all rights, a road like this ought to be a freeway with grade-separated exits. But of course that's expensive, so this is a "cheap" and worse alternative. ("Cheap" is in scare quotes because it's still a wildly bad investment compared to just having sane non-sprawl-y urban planning to begin with, so you wouldn't need so many ought-to-be-freeways everywhere and could afford to build fewer of them properly. This is the "solution" to a problem that shouldn't exist.)

I know roundabouts in the US are considered socialist (or some other comparable reasoning)

American traffic engineers are coming 'round to roundabouts, actually!

That said, an intersection that's a good case for a roundabout is pretty much the opposite of one that's a "good" case for a Michigan left. Roundabouts are well-suited to situations where the major and minor streets have relatively similar traffic volumes and/or a lot of left turns, whereas a Michigan left is "appropriate" when you've got a low-traffic minor street crossing a very high traffic major highway, and left-turn volumes are low enough that you can treat them as an afterthought by exiling them to U-turns down the road.

Also, single-lane roundabouts work fine, but multilane roundabouts can get a bit iffy, especially at the extremely high traffic volumes and design speeds of the sort of road where a Michigan left would be considered. We're talking about places where the major road might three lanes in each direction and have a 55-70 MPH (~100 km/h or more) speed limit, with those cars only having to stop occasionally when a car on the cross street trips the actuated signal. In a case like that, forcing all traffic to slow down significantly for a roundabout might not be seen as acceptable.