If a lock is neglected and left in a broken state for an extended period of time, the integrity of the hardware of the door is in danger of being compromised.  This is important to note, especially if the lock is still somewhat usable, because people tend to let locks be broken for too long.  This then caused damage to the structure of the door – especially where the latch is and the wood surrounding it.  Rather have broken locks fixed than having to replace an entire door.