I have maybe a dozen knives with the combo edge. And perhaps a hundred without. All of my users are without. The combo edged knives are just interesting collectables, patterns that my favorite cutlery made in a series, and needful to own to complete the series. I never found a need for them in my users, and even with the Wonda-Edge, a Schrade single side grind which easily resharpens, the serrations just bother me when I am trying to make a smooth cut. Serrations are great for cutting a t-bone steak, but that is about the only time I like them. To me, they are annoying bling-bling like guthooks.
Codger
Edited to say: Personal preference is the main reason for me.