In the 41 years we've been growing cacti we've seen various plants go in and out of favor. It's been that way with Mammillarias. True, the flowers on some Mams aren't especially flamboyant. But flowers aren't everything. Take Mammillaria matudae. The flowers are purplish-red and about 12mm long. Certainly not flamboyant! But taken together, as a ring around the plant, they stand their own.
The plant itself, however, is to this old man's eyes, quite outstanding. There's a symmetrical beauty here that has always fascinated me. And, for the life of me, I can't understand why they ever go out of favor.
But then again, I'm that old man with a beard who thinks it's no big deal - just another day in Portland, Oregon - to accompany his wife for a drive along a main drag (overlooking the city) behind a miniature horse with a couple of Belgian Tervuren dogs along for the jog!