We need the information for census data.  You can't track how races are doing if you don't keep track of what race people are at all.  It's also important for inclusion reasons.  For example if we know a city has 70% white and 30% black, but all the good public schools are 90% white, we know there is a problem.  Not collecting racial data is detrimental to racial equality

African American is not used that much outside of statistics and formal situations