Caffeine is something that is important to certain people, such as those diagnosed with Anxiety and/or Bipolar Disorder. They are advised to stay away from caffeine, which is hard to do currently.
Also, there are numerous people who simply wish to avoid caffeine.
It is, technically, an addictive substance. Other addictive substances are Regulated, such as Nicotine/Tobacco & Alcohol. Caffeine should not be disregarded simply because it is popular.