I suppose it's a request for 2 features, although when I wrote the title I was just thinking about embedding a web-browser.
Important note: this would all be optional, users could bypass this program and do it the old fashioned way without aids if that's what they want.
1st feature
Place a web-browser within the download application, for convenience. To explore GOG store and use GOG forums and view news events.
2nd feature
Expand downloader's functions. I suppose it wouldn't be called downloader anymore. Not just manage downloads, but also manage what you have installed as well. Basically provide a list of what is installed with shortcuts to un-install or play, or to open a folder window to the installation. Also provide a list of games you bought with links to install, and have games greyed out that are bought but not installed.
Ya, OK, like Steam. However, unlike Steam, you could bypass this 'game manager' entirely and just download from gog.com and install manually, and it would be DRM free.