You can mess roundabouts, but it requires a sever lack of competence that we rarely see TBH, and it can be progressively improved (signage, better visibility, lines etc)
I'm with you on how some will still be dangerous, and can require traffic stops. But it's still better than going back to a plain stops IMHO, and it's usually in portions where it was already dangerous before putting in the roundabout. In practice I've never seen a reversal of a roundabout to get back to a plain intersection.
I don't think most of the ones here could be easily reversed, for what it's worth. The streets were designed with them in mind, so they're usually at the exact spot where 3-5 different roads intersect.
The number of bad roundabouts is pretty common here, though. But it wouldn't entirely surprise me (based on other things I've seen) if there was a level of local incompetence that went beyond the norm. You're right that they can be improved, but (I mentioned this in another reply), sometimes that takes years or decades for whatever reason (and even then, they don't fix all of the issues).
I'm with you on how some will still be dangerous, and can require traffic stops. But it's still better than going back to a plain stops IMHO, and it's usually in portions where it was already dangerous before putting in the roundabout. In practice I've never seen a reversal of a roundabout to get back to a plain intersection.