Honest question: Why should there even be a class restriction for races? It is just a label that is put on a char ingame, and it limits te options for customization pretty hard. For RP and immersion purposes it is interesting for myself which race I choose, but ingame reading a label on another toon pretty much breaks immersion, and in RP I am only intersted in what the character tells me about himself, not what the game labels it.
Restricting classes to certain races is, well, racist, and neglects all thoughts of people moving from one country to another, from people who travel, learn new things from foreign cultures, marry and have kids with people from other cultures. It would be really cool to be able to play every possible combination. The game itself is not consistend with the race restrictions, why should we be forced to it?