Citizen Wingman, ca. 1997

Citizen and Casio cannot? Seiko can! Why?

Why do Citizen and Casio rubber straps consistently crack after 5-7 years? Why do very inexpensive rubber straps that come on children's watches last for over 20 years? Why does Seiko's rubber never crack? Many questions I know, but I am not a chemist, do you have the answers? Please mail to, I would really love to know.