I can easily see the status of my garage door (open or closed) from anywhere. Solves the problem of "Did I forget to close the garage door?" (and the number of times the answer to that question is "Yes" is > 0).

I can open the door from anywhere to let someone in if they've forgotten their keys (times I've done this is > 0).

I can enter the house through the garage if I've forgotten my keys (times I've done this is > 0).

I have given access to my house to a houseguest without giving them a set of keys to my house; I easily revoked this access when they left.