If you have problems keeping up with your rotations: OCDs, GCDs, DoTs, then macros will be of benefit to you. They take some of the thought process out of managing your skills, and decrease the buttons you have to press.

If you do not have problems manually keeping up your rotations with efficiency and you don't mind pressing lots of buttons, you will achieve higher DPS than with many of the "One Button Macros" you see floating around.