I think it is usually a matter of aesthetics, with the bias towards the purer and cleaner lines of PE's. Also, people like the versatility of having a nice sharp clean blade in all different places in your EDC, because sometimes you want the tip, sometimes the belly region, and often the heel of the blade for close-in detailed stuff. I have always disliked SE or CE for both these reasons...HOWEVER, I recently carried my CE Tenacious around for a week or so at a beach house, beating on it for all sorts of tasks in and around boats, the beach, and wooded areas near-by. In this case I was carrying the knife purely as a hard-use tool with no thoughts to aesthetics, and I was really surprised how viscous the serrated part was in tearing through anything I threw it at. Granted the serrations were still factory sharp; but honestly, there were times when they cut faster than a sharp PE would have purely because of the aggressive contact angle that the serrations put the cutting surface at relative to the thing being cut. It tore through branches and wood, old salty rope, fabric, and fish. The fish in particular is a good example of a situation where the serrated part will out-perform a PE, no matter how sharp, for all you doubters, because you need to get through soft bits and skin (easy) interspersed with bone and cartilage, and you want to do it immediately while your mind is on other things.
So, IMO CE can indeed be very useful for hard-use in a varied environment when you don't have time to mess around. That said, I never buy CE or SE for my normal knives because, honestly, for most tasks they are just ugly, unnecessary, and pain to try to use. Especially the ugly part -- you aint never gonna see the beautiful lines of a katana broken with a serrated section.
