I just have a problem with sending luggage through unlocked and got tired of using zip ties then finding a knife to open the darn things as I can't take my knife anymore with me.

Wherever there is a thief, I would think an unlocked bag would be a better target then a locked bag and any luggage lock could easily be broken off so nothing is perfect. It's a small sense of security for me given the number of people that have access to the bags prior to reaching screening and getting on the plane, then all the connections and such. Due to all my normal connections, I can go a day and a half without seeing my luggage on my flights, so I got the locks that change colors when a master key has been used to open it, so I know if anyone has opened the lock besides me.

Of course, I've lost items out of luggage even before the 9/11 changes, once burned etc....