Why?

Why does it matter if there is any relationship between race and profession? Consider a game where choosing your class determines your race, or vise versa. These games do exist, but why do they exist when there are games that give you choices as well? Is one method better than the other? These are the questions I considered when choosing this project.
From a programmer's perspective, it would be easier to set a race and profession combination and then move on, but it seems to be just as easy to create race and profession such that they can be chosen by the player. The character would seem to use the same amount of storage, simply associated with the player's choices. There seems to then be no real reason as to why set race-profession games exist, unless you consider the player side. There is the chance that players associate certain races with certain professions. If the majority of players would choose that race-profession combination that is set in one game in another game that has the freedom to choose, is there any benefit to keeping that freedom there when most people will "ignore" it? That is what I intend to find out through this project.