I see where you're coming from, but the commercials I saw all said, "Now only $399!" rather than, "Now available without Kinect!" Whether it was a legitimate price cut or not, MS certainly tried to position it as one.
If we're discussing the potential effect of back-to-back price drops on public perception, isn't the public's perception of the initial cost-of-entry reduction kinda the only thing that matters?
"Two price cuts in a row? Reeks of desperation
"
"The first one wasn't a real price cut! We just wanted to trick you in to thinking it was cheaper! Now it really is!!"
"Err
"