I believe it is because to the common man, philosophy solves none of the pressing problems at hand.  Now the common man hardly reads philosophy, so there must be something else.  

There is.  If philosophy had answered them (he argues to himself), then the philosopher would have gotten off their arse and implemented their solutions already.

The real question then, is not why the common man isn't interested in philosophy, it's why philosophers aren't interested in applying their philosophies to the world's problems -- because they have philosophies about all of them.

Alas, there seems to be one answer left:  they must either be cowards or lazy turds.  And that view of philosophers paints and taints *philosophy itself*.