A carbon fiber rod is not necessarily better than a glass fiber rod; the two fibers have different properties, with their own trade offs.
Carbon fiber is less flexible (stiffer) than glass fiber and more brittle and prone to breakage when misused, while carbon fiber allows for longer and faster rods. Carbon fiber also allows for a smaller diameter rod that is more sensitive than a glass fiber rod.
A carbon fiber rod is also much lighter than a glass fiber rod allowing for longer days of fishing.
Each has its purpose in the fishing industry and both improve an anglers chances of being successful when the blanks are used for the right purposes.