4. A Viable Threat
The Marvel Cinematic Universe (MCU) is teeming with heroes: besides the ever-expanding Avengers there's Nick Fury and SHIELD, and, with the Chitauri defeated and the wormhole closed at the end of the first Avengers movie, they need formidable enemies and they need a lot of them. Enter HYDRA. HYDRA need to be made into a viable threat to SHIELD and the Avengers equally. We as an audience need to see them as capable of causing real harm to the world and being able to damage SHIELD and the Avengers, rather than merely posing as threats like the useless battle droids from the Star Wars prequels. We need to see the vast resources available to Strucker and HYDRA and their global reach as well as their unrelenting will and focused aim toward achieving their goal of creating a fascistic New World Order. Strucker needs to be both ruthless and ambitious rather than an archetypical cackling bad guy, and it would even be good to see the villains triumph (however temporarily) at the end of one movie in order for us as an audience to take them seriously. The Chitauri were ok for The Avengers but, upon re-watching the movie, were they ever really a threat? And what was their goal? They rode around New York City on flying jetboats and whales all to mess up some offices - Strucker and HYDRA need to be much more effective than that!