Question: were you using Siri back when it first came out?
It seems to me that a lot of people ignored Siri or any AI until Apple bought and used it.
But that's because it wasn't integrated so you had to go into an app in order to use it. I have the same issue with foursquare where I'll use it for a couple days but get tired of having to open the lock screen, find the four square app and then check in.
Siri is baked in so I don't even have to pull my phone out of my pocket if I have headphones and do stuff. Imagine how much more check in apps would be used if you could check in with Siri when you walk into some place.
Again, convenience is key.