The real problem, I think (based on what the EA folks over the feedback forum have said), is that most of the critical problems people have with these forums - sorting, no page numbers, nested replies, no custom avatars, etc. - are all fundamental ways the new forums work. They can't be fixed, because they aren't actually broken. They are quite literally "features not bugs."
I hope I'm wrong or misunderstanding something, because if I'm not the only real fix I can envision would be for EA to scrap these forums and start again with another new backend. I don't think that's likely.