Blizzard devs have posted a short note in this week's hotfix update to World of Warcraft. In it, they explain that the 1-20 "low level" experience has been gradually being tuned over the last couple of weeks that add some modern conveniences to the earliest levels of the game and that the pace of combat has been adjusted.
According to the blog post, these adjustments are only the beginning of changes to be made throughout the leveling experience in the game. More will be incoming in the future to tune pacing and tuning.
Read the full notice on the World of Warcraft community site.