Nog Robbin
Scholar
I guess the biggest reason for the PC to be mostly quiet is that it allows the player some say (or thought) into what they're character is actually saying. To give enough options to the player for them to be able to choose the one that suits the character they are playing, and for those then to have appropriate consequences within the dialog and the game would mean some large... very large dialog trees.
Hence NPC's who are entirely the game designers creations can have dialog that suits them.
I don't believe a free form text system is viable yet either - not without some serious misunderstandings between player intent and the way the NPC interprets it. I still feel (for player dialog) that an action/wiki system combined with emotion/intent would produce the most versatile system from a player point of view. Sure - you may not get to see *exactly* what your character says, but from the options you select when creating his part of the conversation you'd have a good idea in your mind of what was said.
Hence NPC's who are entirely the game designers creations can have dialog that suits them.
I don't believe a free form text system is viable yet either - not without some serious misunderstandings between player intent and the way the NPC interprets it. I still feel (for player dialog) that an action/wiki system combined with emotion/intent would produce the most versatile system from a player point of view. Sure - you may not get to see *exactly* what your character says, but from the options you select when creating his part of the conversation you'd have a good idea in your mind of what was said.