Very interesting, although anyone who writes "essay" as "essai" needs to be banished to somewhere a long wai awai.
Actually, I think those are very valid points. Epic has a tendency to diffuse into soap opera with knights, and the lack of forward drive probably is, as Scalzi says, the result of spreading things too thin. One of the main questions in any story is surely "What has to happen to end this story?" I lost track of what the answer might be in ASOIAF a long time ago and as for Jordan, goodness knows. One way or another, everything has to drive the story forward, even if it does so in a rather unexpected way. If you need two pieces of a magic sword and there are three characters, it seems like a waste of time not to send two of them together to get one of the bits. However, if they have to all have chapters, the two-person group will need more stuff to do because it will be getting more screen time.
I think a good plot is often a simple plot approached from an oblique angle. So, you might have a story where a villain plans to rob a bank, but the real story is how his lodger's girlfriend starts to suspect that something is going on. What we see is through her eyes, and is all the more menacing and compelling because we don't have the full picture. Epic runs the risk of giving the reader the full picture to no real advantage. I don't mean to say that epic has to contain twists and surprises in order to work, but I'm not sure that all stories need to be told from more than one viewpoint unless something really new is being added.
That said, I don't think the reader has to know what the end of the story is, just the writer. So long as the characters clearly get deeper into the meat of the story, and don't just have endless little side-quests, the feeling of progression ought to be enough.
Thanks for finding this.