There are two reasons bathing suit manufacturers chose the word spandex and continue to use it in their swimsuits.
The first reason takes into consideration the thoughtfulness of the manufacturer…it's to oblige weight fluctuation. As I put on weight over the winter, the spandex accommodates my changing shape. I call it my winter expansion program. Bathing suit manufacturers are well aware of the program and market accordingly, which brings us to reason number two.
Manufacturers are well aware that after prolonged use, especially in a chlorine pool, spandex loses its elasticity. It's not pretty after that. Gravity takes over and everything migrates toward the equator. At that point, it's time for a new bathing suit, which is exactly what the swimsuit manufacturer's plan was all along.
As I continue to age, my winter expansion program and the laws of gravity make spandex a necessary requirement in my swimsuits. The fact is my bikini days are over, folks. I gracefully accept that fact as I look forward to thoroughly enjoying the summer either in or out of a bathing suit. And you can take that any way you want.