Based on your post it sounds like you have created a hosting mechanism for service logic. The MSE doesn't host service logic, it provides a management layer in front of the service logic so that you achieve several benefits:
1) You can change the service logic without impacting a consumer - the MSE is an interception layer between the consumer and your actual service. this interception layer can massage the messages to make sure consumers aren't impacted by your
service logic changes.
2) You can expose the capabilities of your service logic in alternate message formats, protocols, and security contexts - the MSE can be the layer to enforce transport/message security, perform authentication and authorization, or expose your
capabilities over TCP, Http, SOAP, POX, etc.
3) You can implement logging and auditing within the MSE layer to provide a means to record/track the # of executions, performance, and who is using your services.
Much of this is handled through the notion of a policy. This allows you to create one of the desired behaviors mentioned above as a policy and apply it accross any endpoint the MSE exposes without requiring any changes to your service logic.
There are many other benefits, but I'll just stick with these for now to make sure I've answered your questions.
Make sure you've gone through the MSE Walkthrough in the Exercises.zip file in the installation folder. This should give you a pretty good overview of the key benefits.