Just like AOT compilation with PGO data.

Well, it's a trade-off. If someone compiled the C++ app for your architecture, sure – if not, you need to figure out how to compile it and depending on the compiler and set of headers you have installed, it's not always easy. When I say, not always easy I'm being generous, there have been cases when the function signature was different between the sets of headers the author had and what I had...

In Java's case if you have all the class files, all you need is the JVM for your architecture. You don't need the program's author to compile it for your architecture.

And finally, JVM tuning does not need to be performed by the user, but can be performed by the user. The most frequent tuning needed to be done by the user was the maximum memory that the JVM could allocate, but that hasn't been needed for a long time (since Java 8, I think). Now the JVM, by default, has the sensible behavior to allocate as much memory as the OS will let it, when asked by the application.