They don't make any sense since
- they are not required for bundled plugins (com.intellij.ide.plugins.IdeaPluginDescriptorImpl#myVersion will be filled with IDE version)
- they will be overwritten during the build for pluginsToPublish (org.jetbrains.intellij.build.impl.DistributionJARsBuilder#setPluginVersionAndSince)
Still they may affect plugins loading mechanism, e.g. see https://youtrack.jetbrains.com/issue/GO-6741 or https://youtrack.jetbrains.com/issue/IDEA-188964