The concept of a “protagonist” is in this day and age sometimes misconstrued--or, at the very least, spun in a noticeably biased, positive way. For many, it refers to heroes: people who, flawed or not, are ultimately good people that we come to like, understand, empathize with, and cheer for. When people hear the word “protagonist,” they usually think of the likes of Harry Potter, Forrest Gump, Superman, Odysseus--you get the idea. It all really goes back to the way we see protagonists in most forms of fiction.
Technically, this perception is not correct. Like I said, it’s biased; it’s mostly influenced by the positive figures that are selected as the protagonists of many forms of fiction, from television to literature to film. A protagonist in the classical sense is the main focal point of a story: an individual of various gender, race, species, and so on that serves as the connection between audience and fiction. There’s nothing in the classical definition about being good, or even being likeable--at its core, the protagonist exists to help draw the audience in and immerse them in the world of a story.
With that being said, though, at the end of the day, labeling characters as likeable or unlikeable isn’t necessarily enough to determine how interesting, complex, or engaging the characters are. Which brings me to my point: I think it’s unfair to assume that an unlikeable protagonist “isn’t supposed to be liked” and thus doesn’t deserve criticism.
Ultimately, I know this all comes down to a matter of opinion, but too often I see people trying to defend characters because you’re not supposed to like them. What really matters when it comes to a protagonist or to characters in general is whether or not we care. After all, part of the reason people enjoy fiction is because of character; character represents a tether between reality and a world we only see and/or hear.
For me, I want characters who experience some kind of change, who evolve over time, who discover something about themselves for better or worse. What I don’t want are pretentious characters that are supposedly “dynamic” or “original” because they aren’t meant to be liked, and it’s here that I think some writers falter when they want to make a protagonist that isn’t a goody-two-shoes or something similar.
When most people say that they “don’t like a character,” what they’re really trying to get at is that they don’t have a connection to that character due to what they perceive as problematic character development--something that the aforementioned defenders don’t really get.
What happens is that sometimes, an unlikeable set of characteristics just turns us off from following the story or caring about the plot. Remember, characters are tethers between us and a story; if we lose interest in a protagonist or group of protagonists because they're just plain uninteresting and overly flawed, what's the point in continuing?
Think of it this way: just as we often say that a perfect character is uninteresting and not conducive to an effective story, so too is a protagonist who is full of flaws and has not one redeeming characteristic that makes us intrigued or urges us to reflect.
It’s not that it’s impossible for an unlikeable protagonist to ever be effective; in fact, look no further than the likes of people like Tony Montana from "Scarface." That said, there are limits. The ones that don’t work get the flack that they get because the unlikeable aspects prevent us from caring.
Again, this all boils down to opinion, but the one thing we have to realize is that using the fundamentals of a style to bring down criticism of how that style is used is silly and needlessly resistant to change.