The Marvel Cinematic Universe is famous for having incredibly lovable and awesome heroes, and typically flat, underwhelming villains. It mostly boils down to the fact that so much of the movies' time is spent with the protagonists, not the antagonists. Marvel Studios works hard to make you really embrace and empathize with the heroes, and that's partly why its movies are so successful. The fact it under-serves the bad guys has been noticed and criticized by viewers, though, resulting in the idea that the universe has a "villain problem." Will Avengers: Infinity War manage to make Thanos, and his servants, an exception to this problem? Or will they just add to the franchise's long list of boring, CGI villains?
So Many Villains
Thanos, the big bad that's been teased ever since we saw the post-credits scene of Avengers, will not be the only powerful being going up against the Avengers, Guardians, and friends in the movie. The Black Order, comprised of "children" of Thanos, will be doing a lot of Thanos' dirty work to retrieve the Infinity Stones.
The Black Order includes Corvus Glaive, Proxima Midnight, Ebony Maw, and Cull Obsidian (renamed from Black Dwarf, as he's known in Marvel Comics). Only introduced in 2013 in New Avengers, the Black Order is a group of intergalactic, deadly worriers that each boast their own specific skills and abilities.
Infinity War will have to spend time with each of these members for the audience to connect with them on any level. Even Thanos, who we've seen a couple of times in post-credit scenes and cameos, is undeveloped and mysterious to those who haven't read any comics with him.
The film will really have to work hard to establish Thanos as a character that the audience can invest in, or he'll just fall flat. His motivation is relatively simple: he wants to level and rebuild the Universe on his own terms, and he needs the six Infinity Stones to do so. He has familial ties to Gamora and Nebula, and Drax has a personal vendetta against him, so hopefully these dynamics will be explored to replicate the success of Hela in Thor: Ragnarok.
So Many Heroes
Avengers: Infinity War is going to feature the largest roster of Marvel heroes in a single movie to date. Combining the ever-growing Avengers members with the Guardians of the Galaxy already results in almost 30 heroes, but adding Spider-Man, Black Panther, Doctor Strange, and supporting characters to the mix means there's a ridiculous number of heroes to juggle. Joe and Anthony Russo, directors of the Avengers: Age of Ultron sequel, have a huge task on their hands doing justice to these heroes as there as just so many to use.
There's no point bringing in popular characters such as Spider-Man if they're not going to be utilized properly and given an ample amount of time to shine. The problem with balancing so many heroes is that there's a lot less time for the villain, or villains in this case, to shine. How can Thanos and his Black Order be developed and interesting if so much time is given to the people they're facing off against? There's a chance that Infinity War will have a hero problem, not a villain problem.