I think the main reason they are allowing us to change (an it'll be a one time only thing from what I understand) is because some race/class options weren't available when we started playing the game. For example: maybe you wanted to be a Roegadyn but are a girl and don't like playing cross-gender...well then you might have selected Hyur or Lalafell instead. I think the decision is based more on this than a drastic change to how our characters will look.