1. Because his mother was listed as "Single". (His father's student visa application documented that he was already legally married in Kenya to Kezia Obama.)
2. His name on the original birth certificate was "Barry Dunham".
3. Revealing 1. and 2. would destroy his "Dreams From My Father" illusion.
This case continues to grow legs. Also, Obama’s birth certificate may display a bogus address further adding fuel to the fire.