Why? Reason #1: It's on when I'm still at work. However, I would not watch this quack even if his show were in prime time. That leads to...
Reason #2: He's a quack, promotes nonsense, unrelated (or even worse, contradictory) to the current medical knowledge, and in my opinion is a disgrace to the medical profession. If you ask me, he should be stripped of the M.D. title. At least he would not be going around, pretending to be a doctor and disposing dubious advice (faith healing/reiki, anyone?).
I'm no medical expert, but I want to be able to trust one. That's why I expect those titles to mean something. When I need to see a doctor and get his or her advice, I do not have time to do extensive research on their medical opinions. I have to trust that they follow established facts and current research, not some out-of-this-world fad that just happens to sell well at the moment.
Dr. Oz is the negation of science and reason. He promotes what sells and makes his TV show look good. He can do it as much as he wants, but should not be allowed to do it as a doctor.
Interestingly enough, I might make an exception and DVR his show on Tuesday, April 26. Why? Because he will have Steven Novella (from The Skeptics' Guide to the Universe podcast). As Orac suggests, the editing might change the actual message, but it's good to know that a hard-core skeptic is invited into the "devil's lair".
It should be interesting to watch.