As a software developer (on a product that has a larger user base than the kindle) I’m going to call B.S to the idea they want to reduce support issues.
IMHO the people that are smart enough to download and install the update are the more tech-savvy users... i would think those are the people you want testing the software first. People like my mom don't care what firmware they have and wouldn't even notice if they got a new version over wireless.
I've had my wireless on since the update was first announced... still don't have it
~Brian