I would bet the suggestion for a 1.25" hitch for an Element is to make sure people don't try to tow something over the limit for that vehicle.

I was just doing a little research into this as I'm getting really tired of the roof rack for my Mazda. I would need to put a 1.25 hitch on it and then get a tray rack. We need a new rack for our SUV, which has a full blown 2" hitch. I found out that adapters to go up are only about $15.