There can be several reasons why people might not want to wear flip flops or sandals, including:

1. Lack of support: Flip flops and sandals typically do not provide enough support for the feet, which can lead to foot pain, especially if worn for extended periods.
2. Risk of injury: Flip flops and sandals offer very little protection to the feet and can increase the risk of injury from objects or uneven surfaces.
3. Hygiene concerns: Flip flops and sandals can easily collect dirt and debris, making them less hygienic to wear, particularly in public places like pools or locker rooms.
4. Climate and weather conditions: In colder climates or during inclement weather, wearing open-toe shoes can be uncomfortable or impractical.