As I was saying before, this technique was an established crutch to help Eclipse deal with Maven in the pre-m2eclipse days. Eclipse cannot have nested projects. Therefore, when you use eclipse:eclipse, the parent gets excluded from your Eclipse workspace and you can't edit the pom.xml file there or use the Team support for SVN update. So, developers established this workaround by positioning the parent adjacent to modules so everything makes it into Eclipse.
http://maven.apache.org/plugins/maven-eclipse-plugin/reactor.htmlBut now that m2eclipse allows for nested projects, we don't need this workaround.
-Dan