Game engines can afford to be generations ahead : they might even be targeting specific hardware (single console release), they typically assume a sandboxed env

Game engines can afford to be generations ahead : they might even be targeting specific hardware (single console release), they typically assume a sandboxed environment that they are in total control of (at best, they'll make a limited and tightly controlled GUI framework for modders), they might have restricted themselves to a limited number of inputs/outputs (single screen with a specific resolution, gamepad only), they don't have to worry about unknown unknown uses by other developers... None of these apply to a generalist renderer, therefore it can only "lag behind" the game ones. (Unless maybe if we're talking about the "human side of the question" : what are the best designs, layouts for a generalist human/machine interface ? Here it's the generalist GUIs that I would expect to be a couple of generations ahead (Xerox' labs, Apple's Macintosh, IBM's Common User Access standard, CERN's World Wide Web...)