Although this was discussed before, I want to raise again that the behaviour of the IntelliJ installer is not acceptable with respect to installed plugins.
I use the option to store the IntelliJ configuration in the IntelliJ home directory. Now, to avoid reinstalling the plugins I just renamed the plugin folder, hoping that it would not become deleted. Unfortunately, everything in the exisiting directory is wiped out, even if directories do not match. This should not be, renamed directories should not be touched.