But what you’re suggestion is rather than just those who need the game name doing the lookup, that Twitch add that extra processing internally to ALL Get Streams request, regardless of if developers even need it.
As it currently stands any internal systems at Twitch would only need to provide just the game ID and not do any further lookups, and just those developers who need the game name/box art can request it Those who cache that data (or simply don’t even need it) aren’t being sent data they don’t even need, and Twitch wont have extra overhead on unneeded requests internally.