"Unnecessary complexity" means having things or situations that are more complicated or confusing than they need to be. It refers to adding extra difficulty or complication to something that could be simpler or easier to understand. Full definition
There is still a lot of unnecessary complexity swirling around the notion of equity. (ecoequity.org)
Lots of small businesses do not use lawyers because they think that lawyers are going to add unnecessary complexity to the job and charge too much. (lawyer-monthly.com)
Many times, real estate agents and other experts attempt to be clever, think outside of the box, and consider unnecessary complexities in their evaluations. (baylor.edu)