Why did bra burning not last as long as the silly saggy pant fad?

Why did bra burning and going Au natural not last as long as the stupid saggy pants thingy (cannot bring myself to dignify it by calling it fashion)? I think women burning the bra and going natural was one of the truly independent thing women has done for themselves, but why did they not keep it up? Why did they eventually cow down to society and cumber themselves back again in the Spandex/Lycra chest harness contraptions?