There's no Nitro to turn to if the wrestling fan has read spoilers. We have seen a production quality difference between the live Raw and taped Smackdown that can be owed to post-production for the most part.
Is it a money issue? I think it'd be more expensive to run live.
Is it an issue of "shock value"? What has shock value done for ratings over the past year without competition?
1) habit. why break a good routine if it's working?
2) logistics. Live monday, tape SD! tuesday, rest of the week for travel/house shows + the monthly sunday PPV.
3) shock value. that "never know what will happen!" vibe
4) if the PPV is sunday, when would you tape RAW? monday afternoon? (well, never mind the fact that it's live at 9pm est, 6pm pst if they are "live" in cali, but still. would you go to a 2pm, or 3pm taping of RAW? ) imangine the talent wrestling some time bewteen 8-11pm sunday night and then wrestling again 12 hours later?
keep it live.
Wrestling has been rhyming with ass. I miss shows and it makes me all shades of ambivalence. WWE is starting to suck again. The crops? Jeezum Spice! Someone stole my crops. What in the ham fat is going on. That's just poo-doo! That's just my 2.4856 Yen.
Keep it live and make SD! live, too. That way, when SD! continues to bring the awesome, JR can no longer claim in the Ross Report that it's because they have the "safety net" of being taped and edited.
also relevant, you can see Herb Kunze slowly lose his patience with the direction that the WWF went in back in the late '90s. Also, the podcast Joe vs The World has some really good retrospectives of WWF for 1990 through 1992.