I suppose I should mention that the entire debate in the United States over whether or not to call it 'soda' or 'pop' stems from the early days of it's invention when it was called by its full name, 'soda pop'
Colloquialisms being what they are, everyone and their cousin jumped on one side of the fence separating the vast fields of etymological simplification and, regional trends being what they are, have remained on their respective sides to this day.
It's no different than the reduction of any other of the many terms in the English language (text messaging...texting, electronic mail...e-mail, web log...blog) only there's more than one direction it can take