I've never seen any plugin do this, and without any warning.
First, the location of saved presets is wrong, user presets should be saved by default in the documents folder and it should be easy to customize that location.
Second, your preset installers (and the plugin installer) shouldn't include the Mac DS Store files when installing on Windows.
Third, uninstalling should never delete user data. That data should be stored separately from any plugin specific files that should be removed when uninstalling.
Also, when installing a new version, whether by using the updater or complete installer, leaving the old versions listed as installed apps is bad.