Twistoflex - why? Still relevant?

Most jewellery stores stocked them, and believe it or not most general jewellery stores still stock those racks of same branded leather straps in several sizes.
Was looking for a strap local several years ago and have about 7-8 different jewellery stores (zero watch boutiques or ADs) and all had similar lower quality racks of straps. Not one had a 20mm strap.
And yes a few had modern Spiedel twisto-flex still in stock.

As a product of the 1960's, I can attest to earlier comments that watches were mainly used to tell the time for most people. Most watches were sold with leather straps that only lasted a year and the Spiedel and JB expansion bracelets provided a comfortable alternative that lasted much longer. Both of my grandfathers, along with my father swore by them.

My father wore a timex but his father had a stainless Rolex OP, and my mother's father had a solid 14k autowind Bulova. Even though my grandfathers valued their watches, they saw the strap/bracelet as simply a means to attach the watch to their wrist. I have a soft spot for these bracelets as they remind me of my grandfathers who first piqued my interest in watches, some 50 years ago. For that reason, I have them on a few of my watches. They only see occasional use, so I don't really worry about wear to the lugs.