Merely replacing the rotors often doesn't cure the wobble caused by lateral runout, because the defect is in the hub. Did they cut the new rotors to match the hub? here's more detailed info:
If the runout was accounted for, then you might have worn suspension bushings. I don't know much about the 7 series, but on a 3 series, worn control arm bushings can manifest itself in front end shimmy when braking at high speeds.