As it is, certain races are forcibly shoehorned into different roles due to a number of different circumstances. Some examples of these include halflings, which rarely become barbarians or fighter, half-orcs who rarely become sorcerers or wizards, and other races that all fill a specific niche and thus come out in cookie-cutter copies one after another. One of the big things that influence the race that one takes according to one's race is subject to ability bonuses and penalties that the race gets. Instead of those, we sweep the table clean and have abilities that are flavorful for specific races, allowing them to be unique without necessarily shoehorning them into a specific class or role.
Read the full text at: Simplified Races