I agree with everything that's been said (and I'm a bootcut/flare fan who's been both wearing and buying them despite the skinny craze). I did notice a smaller variety of options in bootcuts, as retailers made room for straight or tapered silhouettes, and now I'm seeing more flared options coming back.
This conversation made me think of my experience in the 80s and 90s. The late 80s (when I was a teen) were the age of tapered legs. We all had a big poison eye for straight or flared legs. But they still existed--maybe not the bell-bottoms of the 70s, but certainly the straight legs that naturally flared a little at the hems.
Then in the 90s there was the revolt against the taper, but some people continued to wear it--and well... they became known as Mom Jeans!
Which goes back to your question of whether we who still sported bootcuts have been unfashionable in the last several years. Now I'm a mom and I'm 40, and it occurred to me many times whether my bootcuts were the new version of a Mom Jeans. I still think no: because Mom Jeans were not only about an outdated cut, but also about a very unflattering fit. I could see how some of my flares might look frumpy--and I parted with those: the ones with very low waists, wider flares, etc. But I found that the more updated versions, with a mid-rise and a "baby bootcut", looked as lengthening as ever.
Or at least, that's my story and I'm sticking with it!