So I came to a realization today: writers need to be whole-brained people.
This may require some explanation. Most of you have heard of the Left Brain, Right Brain theory, where the left brain controls logic and the right controls creativity - the thinking brain and the feeling brain. (It's a lot more complex than that, but bear with me.) You may not have heard of the other component: the further division into frontal ("higher" processes) and basal (more instinctive processes). This means the brain has four quarters, or:
Frontal Left: Logical, analytical
Basal Left: Order, organization - "the rules"
Frontal Right: Creative, experimental
Basal Right: Emotional, interpersonal
If you're familiar with Tarot, another useful analogy is to align the quadrants with the minor arcana: swords, pentacles, wands and cups, respectively. (If you're not "into" Tarot, this just confused you more. Ignore it.)
Anyhow, I looked at this and realized how much a good fantasy writer needs all of these. It looks like this:
Frontal Left: Construct an internally consistent world where special powers / elements are carried out to their logical conclusion. Plot coherency - does it make sense for X to do Y?
Basal Left: Organize and track information so a character's eyes don't change color every chapter. Grammar, punctuation and sentence structure.
Frontal Right: The fundamental creative juices. Everything from the first "what if?" to the writing itself.
Basal Right: Understand human emotions, incorporate them into the story, and draw them out of readers.
And that's not even getting into the editing process - which, while it may be more of a left-brained process, also requires contributions from the right brain: creative solutions to plot-holes, gut feel about the best route to take ... your mileage may vary depending on your revision process.
So those are my thoughts on the whole-brained writer. Of course, this doesn't have to be restricted to fantasy: all stories require these elements, including worldbuilding ... even if that world is your corner store.