flesh a little more other motiv

Fleshing a little more the 'Other motivations' section

Author: artivis

articles/ros_node_idl.md

@@ -70,8 +70,20 @@ If ROS 2 provided a way for upstream package authors to specify the interface re
 ### Other motivations
 
 Outside of security, there are several fascinating possibilities unlocked by having such an interface.
+
 For example, consider how this could impact [ROS 2 launch][launch_ros].
-It would be able to statically (i.e. before running anything) determine if parameter names or remappings are incorrect, among other similar sanity checks.
+Benefiting from the declared interface(s), it would be able to execute many kind of static assertions (i.e. at launch-time, before running anything) upon the whole system to be launched.
+Such assertions could include:
+- Check for duplicates.
+- Check for multiple publishers on a single topic.
+- Check for message type mismatch.
+- Check for qos mismatch.
+- Check for orphan connections (e.g. a listener is connected to a topic with no publisher).
+- Determine if remappings are incorrect.
+- Determine if parameter names are incorrect.
+
+These assertions results would then be summarized in a logging file for later debugging.
+
 Another example of the usefulness of having a static interface is the ability to create graphical tools for putting a ROS system together.
 Yet another example would be an additional feature in `ros2 pkg create` that would allow a developer to hand it an IDL and have it generate scaffolding for a node with that interface.