Consider it a gift, brought on by laziness...
Previously, changing the front page pic was a somewhat laborious task. Find a photo, reduce/crop, manual editing of the home page code...yuck. That's why it changed so infrequently.
Now, I've just got a directory of photos. Once a photo is copied there, one randomly gets grabbed by the code.
The current photos are from the last three years of front page pics...there's about 40 of them. If anyone sees a photo they think should be added to the rotation, drop me a PM with a link.