Let me regress into geekdom to make my point, to avoid mixing serious literature and WoT. Take the first (in terms of release dates) Star Wars trilogy. Everyone understood the characters' motivations, generally. Sure, the people were a bit simplistic, but Lucas was following the Campbell myth concept, which borrowed Jung's archetypes, etc. Regardless, we understood, mostly, WHY people acted as they did. It didn't matter that the whole thing had aliens and robots and spaceships and even (gasp) Ewoks because the main characters had motivations that made sense.

Then look at the "new" series. Anakin's role was abysmally played, first by the little kid and then by the young guy, and his motivations never made sense to people. As an example (in my mind, one of the worst explanation of motivations in cinema), it took him about 5 minutes to go from wanting to arrest Palpatine to deciding to be evil and start killing kids, with ABSOLUTELY NO EXPLANATION of how he could make that decision so quickly and easily. Sure, they gave him a reason, but it wasn't really properly executed. In other words, the movies were crap because people didn't believe Anakin, all the way from the first movie. And when that happened, they started looking at a LOT of other things that were subpar. Jar-Jar. A little boy flying a spaceship. The racial stereotypes. And so on.

It is absolutely necessary to suspend some disbelief at some level and in some way to enjoy anything speculative, or else you can never internalize it enough to care what happens.