The "problem" is that many women now think artificial support is an anatomical necessity.
Those examples you gave- glasses, teeth fillings, back braces are to correct medical conditions. Normal breast are not a medical condition and people with good eyesight don't wear glasses because they think "it's the proper thing to do" as many women wear bras. As for sore backs, I hear many women say their backs feel better when they stop wearing bras. After all- shoulders weren't design for supporting breasts.