If a conflicting process is running at the time of installation, one can configure the Publisher so that end users will receive a prompt, where they will have the option to close the conflicting processes or defer the installation.
However, for the uninstall the UI Prompt does not appear, and if there is a conflicting process, the uninstall will simply fail. The user won't know that they need to close a conflicting process in order for the uninstall to work.
Would be nice the feature for this as well.
This would then be something similar to the PowerShell App Deployment Toolkit.