As a follow-up to this, the Saurfang subplot is probably the best example of something that works well in a movie or novel but has serious problems in a game.
The first bit of conflict between Saurfang and Sylvanas was in a cutscene, as was his capture by the Alliance, since the Horde PC wasn’t present for it (although the Alliance PC may have been).
Then they had to stuff a random encounter with Saurfang into the Stormwind extraction scenario. In order for us to know what he was thinking, he had to criticize the Horde PC for something we had no choice about (staying with the Horde), because they weren’t ready to give us the opportunity to join him just yet.
Saurfang’s “escape” was then handled through another cutscene because there is no reason for the PC of either side to be present. The Alliance PC would have to be railroaded into agreeing with Anduin’s decision, and the Horde PC is nowhere in the area at the time.
Sylvanas sends the Horde PC to look for Saurfang, and we uncover the traces of proof that he had help in escaping. Good! Solid PC involvement in the story!
But I don’t think I need to go over the mess caused by the next stage, where the Dark Ranger attempts to kill Saurfang and he gets away. It would have been less problematic for the players as a cutscene. But they probably realized that the PC is barely involved in the whole storyline as it is, so they tried to make us part of it, and we all know how badly that turned out. Even the fix of giving us a choice about how to react is clunky, and I think part of the reason is because that plotline up to now has not really been anything that directly affects the PC.
TL;DR: The Saurfang plotline plays out just fine without PC involvement, and when they try to get the PC involved, it gets awkward.