Why would you remove a foot?

A few reasons...: If there is not enough blood flow to keep it alive, if it is too infected to be salvaged, if it it too traumatically injured (usually crush injuries). The main reasons though are infection (especially in bone) or lack of blood supply to be able to heal.

Sounds defeating: Our ability to ambulate is of vital importance to the quality of our lives. Amputating a foot is the absolute last resort, and would only be considered if there is no hope. In short, it would only be considered if the quality of your life would improve without your foot.