Separation of concerns is one of the main tenets of software engineering - allowing developers to reason about software systems in sensible portions, regardless which phase of the lifecycle they are working in. Many researchers in software engineering are actually in the field of aspect-orientation without realizing it.

AspectJ implementations of the GoF design patterns show modularity improvements in 17 of 23 cases. These improvements are manifested in terms of better code locality, reusability, composability, and (un)pluggability.The degree of improvement in implementation modularity varies, with the greatest improvement coming when the pattern solution structure involves crosscutting of some form, including one object playing multiple roles, many objects playing one role, or an object playing roles in multiple pattern instances.