80% build up and 20% payoff is actually a damn good ratio. Many classic movies have a similar ratio. Take Alien (1979). Almost all build up with escalating tension. It's a masterpiece.

The third act fight in 2014 was dark and dusty? That applies more to KotM mate. All the fights here are equally shrouded in darkness and dust and blizzard, if not more so. Gareth Edwards made the smart move of not including too many monsters, and as a result the 2014 movie was perfectly balanced. Anymore and the movie would have been dumbed down.  The story or plot may not be intelligent, but the mounting and execution certainly were.