Correct, org.eclipse.platform is not a "content"
feature (like JDT in the Java package, or CDT in the C/C++
package) that should itself update without being under control
of EPP, nor a feature that users typically should uninstall from
a package (a requirement that some users have, e.g. to remove
parts of Mylyn, just to give an example).
To summarize: The root features are used in EPP to give the
users the ability to remove _some_ content from a package, and
to enable projects to update _some_ parts of the packages easier
If we learn that the Neon structure of the packages isn't
sufficient, or if we see different use cases, we should discuss
possible changes for Oxygen early in the release cycle.