From my standpoint, having played a lot of Multi User Dungeons based on the Wheel of Time story and theme, there is a loss of dynamic forward movement when the player is relegated to an unnecessary role. M.U.D.S. are similar to MMOs in many ways, except they have no graphics being based on text and incorporating imagination and player interaction into the overall enjoyment of the game versus audiovisual support.

The reason most characters are major, important characters in an MMO or a video game is based on the same line of reasoning that most authors make the protagonist's decisions important to the world and other characters.

Would you, for example, have fun playing a game as an Aes Sedai where you sat around drinking tea waiting for the Tower split to be resolved or would you rather take on a role more similar to Egwene, Moiraine or Verin? My guess, is that there is more fun to be had if you had the choice to inhabit a role closer to a major character than a minor, unnamed Aes Sedai/Ashaman/Warder/Whitecloak/etc. Would you make an innkeeper, waiting around for your country to be destroyed and be satisfied with this role after the story has reduced your country to a minor role?

Even the "Lord of the Rings Online" MMO, has the players characters being heroes similar to the Rangers and great adventurers alluded to in the story - the story itself mentioned these mighty people in the background, so even if they are not Frodo, there is enough background lore to convince a player that they are an important member of the storyline, even if they aren't part of the main cast.

The creators of these WoT M.U.D.s have greater insight into the difficulties with adopting the theme and making the game fun than I do, but I'm hoping that whatever happens, interactivity and fun are core elements in their design decision; these are different concerns than what an author telling a linear story needs to contend with.