The information on nets in the PHB indicates that they have 5 hit points.  The DCs to break out of them or escape from them are relatively difficult, but their hit points are very low.  Can a character simply hit the net with their sword for 5 points to escape?  If so, why would anyone do anything different?  Are nets, then, basically good only against unarmed characters?  (Even then it seems like it would only take a round or two to do 5 points of damage with one's unarmed attacks).