It's just a convenience
My husband and I have the option turned on permanently. Mostly I will track him when we are supposed to meet, so I know how far away he is. He'll track me if I'm running late, and I do the same. It just avoids a lot of pointless "where are you" text.
Before we both had cell phones, I used to worry when he was running very late. Now I feel better knowing I can check whenever I need to.
It's only creepy in the hands of creepy people.
PS. I checked the Life360 site and read the stories page. Most people seems to be using it to keep track of their kids. I don't have children, but I can understand the need for this app. When you worry, you worry. It's an irrational thing, and no amount of telling yourself it's fine will make that feeling in the pit of your stomach go away. Having a app that allows you to know someone you love is safe is a huge relief.