RD - The recreation of the letterman incident was just that… a recreation. Look at it again if you get the chance… that’s an older Lawler, a much older Letterman, and a clearly not Kaufman sitting in for Andy (i.e., Carrey). It would have been much quicker, simple and cheaper to build a recreation of the old Letterman set than to try the digital post trick you mentioned. Besides, much of the scene is not shown from the television camera’s point-of-view, which is the only visual record of the actual event that we have. Instead, we see most of it from a vantage behind the camera, or even on the stage itself. And finally, the original incident was shot on video tape. What you saw in the theater was film. Clever filmmakers routinely doctor up high resolution film footage to (sorta) look like low-res video, but you can not convincingly go the other way.
I didn’t notice the lighting discrepencies you pointed out, but that could have been intentional. The cinematographer may have been attempting to recreate bad, early eighties lighting for video. Television cameras of the day required brighter lights than they do now. Much video lighting from that time looks flat, so maybe they went to en extreme to duplicate it.
And just to get back on point… I’ve always had mixed feelings about Andy. Some of his shtick I enjoyed or at least appreciated. Others, I couldn’t fathom. But regardless, I never wanted to see him stop. Even if I didn’t always like him, I was glad someone was out there stiring things up.