Currently, uninstaller can be either on or off using following setting in info element.
<uninstaller name="uninstaller" write="no"/>
But there is no setting which can do this on certain condition or dynamic variable. One of the usecase is that if you are just upgrading the preinstalled software, uninstaller is not really needed.
A condition can now be specified on the uninstaller element. If this condition is evaluated to true, an uninstaller will be created, otherwise the creation will be skipped.