Why? Colleges can admit whomever they'd like.
The larger fact is that, to this point, every president has been a man of some note, throughout his entire life. Each has had a long history of visible and verifiable life experiences, as well as innumerable aquaintances willing to come forward and say, "I knew him when..."
Obama has practically none of that CV.
Presidents, by the very nature of the job, are very public men, having led very public lives. What we have now is redolent of something else.
Not only willing, but **honored** and **pleased** to say, “ I knew him!”