So if you haven't already, try both the on/off options just to make sure.
I don't really see much of a need to rotate the home screen, but I wouldn't complain if it was added as an option.
Also, when testing if the screen rotates, make sure to hold the phone so that the screen is facing out/vertical (not directly up or down) because you know that rotation sensor doesnt work well at all when phones are level/flat.
The home screens did rotate into landscape mod until a few days ago. they must have sent something down to change it. check the video out on the motorola page if you dont believe me. mine did it and hundreds more. now it will no go into landscape mode for the home screen, phone, contacts