This came as a request from a medical client early on. The point is, that the Managed connector is suppose to start a container, and not just connect to one(that's what Remote connectors are for). Previously the Managed connectors would check if the ports were active and use the one found or start one. The problem with this is that even tho configured in your test, your might have another instance that just happens to be running at that time on the same ports but has a completely different configuration, e.g. a DataSource for a stage or production environment.
So if the intent is to connect to a running container, you should use the Remote connectors. If your intent is to start one, then use the Managed connectors.
The AS7 Managed connector is a 'special' case where you have the option to configure the Managed connector to allow to connect to a running instance, but it's a choice you have made.