ROS makes the inter-process communication much easier if the SLAM system is incorporated as one component of a much bigger system. But you don't have to use ROS

ROS makes the inter-process communication much easier if the SLAM system is incorporated as one component of a much bigger system. But you don't have to use ROS for that. We actually provide the ability to run it without ROS. Also, with ROS, it's easier to communicate with sensors given that the sensor drivers have been wrapped into ROS nodes.