I totally understand what you mean. Everything, and I mean everything, ties back to earlier books. I don't even feel like there were plot threads that got left behind or forgotten, there were just so many moments that were built up across multiple books that were ended in a fashion that left me thinking "That's it? I read about this person/thing for hundreds of pages and this is the conclusion?"
It was impressive how Erikson created such a big world with so much history, but then it feels like he didn't do anything with it. I get the impression that he was so fixated on "not doing the normal fantasy stuff" that he forgot to make the books exciting. They were without a doubt impressive, but just not... Very interesting to read outside of an intellectual challenge.
Again, I finished the whole thing and just thought "that was pretty good I guess", which is not at all what I've heard from anyone else. Very ambitious and well done but I'm not sure I would ever recommend it to anyone.