It's been a year since an iPhone was placed in my hot little hand.
Since that time, the amount of times that I've brought out the monster camera (Canon 5D MII) numbers in the single digits.

Is it laziness, convenience, geekery or something else?

It's a few things, actually.
Instant sharing/uploading to the world. On board post production tweaks and filters.... Eventual ease of use when generating books.
The only time I know I have to lug out the monster camera is when the lighting is crap, if i have to zoom to infinity, or if I'm going to be taking dozens of action shots.

The apps available are astounding. The editors are generally awesome. Now I find myself, not looking for the 5D MIII, but for the iPhone 5....

Have you switched cameras?