When my husband and I bought our new house, we knew that we wanted to have the locks changed and rekeyed. Neither one of us felt good about having the same locks on the door even though the house had sat empty for nearly a year. To us, that did not mean anything because people could still have the keys to any of the locks on the doors. We knew we would sleep better at night having all the locks changed. We also wanted them rekeyed because we wanted to have the same keys for some of the locks.
I am an avid runner, and I did not want to have to carry a set of keys with me when I go running.