When trying to install an extension that has a dependency, the Extension Manager will try to fetch it from TER. Since TYPO3Winstaller does not provide an extensions.xml.gz file, the Extension Manager fails and reports that there were network problems. If an extensions.xml.gz file was provided this would seldomly happen.
I do realize that the extensions.xml.gz file would be outdated, but I think this would improve the overall first-time experience of using TYPO3Winstaller. Furthermore I guess it could be easily implemented.