Oracle plans to make the open source JDK Mission Control (JMC) technology available as a separate download to serve both OpenJDK and Oracle JDK users.
Here are some of the reasons why:
To make it available to all Java users
Java Flight Recorder (JFR) is open source now. JFR will be included in both OpenJDK and Oracle JDK binaries starting with Java SE 11. Having a single, separate JMC download for Oracle JDK and OpenJDK keeps it simple.
To allow for independent updates of JMC
As a separate download JMC can be updated independently of Java SE releases. This lets us offer new monitoring and diagnostics capabilities across several Java SE versions at the same time. Features can be added to JMC in the middle of a Java SE release cycle.
It is now possible to efficiently bundle a stand-alone JMC
Taking advantage of the modularity features introduced with JDK 9, Oracle can create an optimized, tailored runtime for JMC. It can include everything needed for that JMC version, such as JavaFX components, while removing everything not required by JMC, making the application runtime size considerably smaller.
Because JMC works with many JDK and OpenJDK versions
Newer versions of JMC can interact with older versions of the JDK (from JDK 7u40 and above). It is common to use a single version of JMC to interact with current and older releases of the JDK. This is made more clear if JMC is a separate download.
To avoid duplication and confusion
It's a common scenario for a single developer to need multiple instances of the JDK in the same system. Having each one of those JDKs include its own, duplicate copy of JMC, when a single version can handle them all, wastes space. It may also lead to confusion as different versions of the JDK may include different versions of JMC, all with (sometimes subtle) differences in functionality.