| Kotath of the Shadde-Quah |
I think alignment is incredibly important. It is a source from which to create and resolve conflict. What motivates one player character may not be an interest for another. This gives the players room to "talk amongst themselves" and find alternate explanations to include the other party members.
When it comes to the antagonists in the game, their personality may align or clash with some of the PC's. Have you ever experienced your party agreeing with and helping further the "noble lord's" goals...only to find that they have been (unwittingly) promoting an agenda that goes against the players code of ethics?
In ROTRL, there is an early ethical dilemma that speaks directly to alignment. When the players delve into Thistletop, they eventually come across a Goblin nursery filled with Goblin babies. This should cause a debate among the players in deciding what to do. Set them free? Close the door? Slaughter the innocents? Use them as bait? I don't anticipate the answer as a GM, but I do expect the players to act as they feel their alignment dictates.
IRL, personalities conflict all the time. It is good practice to find a way to include the people we may not understand or agree with. After all, they may become useful later. :-P