And these actually have been on my mind and been wrestling with in book 4, trying to reorient things a bit.
There are problems with such a long story and trying to balance the different aspects and different characters stories and relevance, and it's particularly difficult when you don't have the complete/final version to work with and can go back and reorder things past and present to sort of smooth things out.
So what happens is you get long sections that sort of fall into certain tracks. So I am working to try to smooth that sort of thing out. In particular the battle and build up took a big chunk of space and time in book 3 where some of that humanity got lost, and there was a lot happening and not a lot of time for deeper stuff, at least in the last half of book 3.
And it's true that some character arcs disappear for a while and may not come back, or maybe they do. In particular I am working on bringing Gastrope' and Jenn back into the picture even as some other fall off and Lenamare and Jehenna etc. But also, trying to bring the Rupert story forward, there was a lot I want/wanted to do with Rupert, Fer Rog and the teen orcs but again so many stories/perspectives getting them all in and doing them justice gets tricky.
But one problem that happens to all of these characters, eventually, is that after time they get jaded as they join the 'in crowd', so to get that human experience, new characters have to come in, or at least that's one option. That is part of Rede's purpose, as we see in book 4, he's getting thrust into an 'inside crowd' that includes people who were outsiders but are now insiders and more jaded, like Vaselle (although he was sort of nuts to begin with, so fitting in wasn't that hard for Vaselle)
So short response is, I hear you, and am trying to work that back into book 4.
BUT the problem is, that means less time for Tom and that also disappoints people.
However, Tom can't get too settled. Because in Book 5 he gets thrust into a new outsider situation, even as he sort of 'comes into his own' at Mount Doom.
Also, I would point out that one should also consider the 'humanity' of less pleasant, more flawed, individuals, even if they seem to be people of power or strength. I am thinking Talarius and Lenamare as particular examples. Talarius is definitely on a growth path and that will be continuing slowly but surely.