I think your comment about story based games probably being less streaming-friendly (that's how I inferred your comment anyway :D) is totally true. However I think this becomes much less of an issue when it is a retro game (NES, Genesis, MS-DOS, etc) because either A) viewers get to relive the nostalgia of a game they are very familiar with or B) get to experience a game they may have only ever heard of, and would not have played to begin with.
Thanks for your thoughts on gaming, as always @whatageek!