Apologies, I have been AWOL for a while. I recently came across a great (IMO) website with some interesting articles on health and fitness, including a number of thought-provoking ones about barefoot and minimalism. Anyway one that caught my eye is linked below. I'd actually been asking the same question myself recently, ie do I really need a pillow and how does it affect my posture (in a similar vein to how barefooting has led me to question the need for foot cushioning). Well, I thought it was worth sharing:
http://www.somastruct.com/pillows-like-orthotics-necks/
http://www.somastruct.com/pillows-like-orthotics-necks/