The old rule where the wild card could not play its division winner was set up originally to create the possibility of rivalry LCSs. The Red Sox in particular pushed for the WC and liked the rule because of the possibility of a Red Sox / Yankees LCS. Probably the other teams saw the ratings potential of Cubs/St Louis, LAD / SF, etc... too, but it really was John Harrington (head of the Yawkee Estate Trust) who pushed the hardest for it.
Now with a 1 game play-in, the thought is that could be a ratings bonanza, too. I think the last few play in games have been great games. The problem logistically is the travel. By having the top seed automatically play the first two at the wild card winner, it simplifies the travel. the only tough thing might be if the WC game were between Baltimore and a west coast team. Then the team with the best record has a decent shot at needing to fly coast to coast quickly and play.