Well, the items in cash shops really cater to different people. There wouldn't be any cash shop items that provide exp up or powerful items if people wouldn't be interested. The demand is there and so companies simply provide the supply. Some people prefer to just have the looks modified while others want it to become more powerful. Personally, I would rather have it for customization of looks.

I want my character to stand out. I can be powerful without item mall stuff. But it's a lot harder to stand out visually without any developer intervention.