I'm all for single speeds. Fixed is fun, but clearly for more of the enthusiast. The ability to coast was a
great advance in bicycle technology that's only, oh, 100+ years old.
I think most bike riders would be much better served by a single speed than the typical 21+ gear wonder commonly ridden.
I suppose the
look of a smooth taut chainline is nice, but there are some great practicalities over derailers, or even sprung tensioners, which I consider a kludge. The single speed chainline is much less likely to get thrown, will last longer and generally needs no adjustment once set.
Coaster brake is my preferred SS ride, simple, cheap, all the negatives of SS and fixed gear combined.