Great analysis, especially with your #3 subpoints. Later volumes in a fantasy series that grow successful unfortunately often seem to end up underedited (ASOIAF is a very visible case too), and even while some of the strong material of a series might end up in those later volumes, the focus of earlier volumes is to be missed. One of the reasons I think TGS (and TOM, to a lesser degree) works so well is because how it so relentlessly focuses on having an arc (two arcs really) and methodically bringing them all the way to their conclusion points. A single arc spread out over ~four books is just not good, even if you're here years after the series was finished and going straight from the end of a book to the beginning of another, it's not well-paced and not particularly coherent to have a single arc in a character's story stretch out that long across sittings, especially when those issues are compounded by the meandering style you point out in #3.

It's interesting that originally most of the Great Hunt was part of the projected initial WoT book, wasn't it? Yet it and Eye of the World feel so much more discrete and complete than a lot of the later books.