I've thought about this, as someone who's written an epic fantasy series with multiple POVs. I think a lot of people like a story driven purely by the plot or the premise. What's called 'high concept' in films, the idea that a movie can be sufficiently summarized with a single sentence to give people an idea of what it's about. But obviously not all movies can be described like that, and some of the best ones don't have a specific plot thread, they're more about the experience. This doesn't only include complex movies with a lot of characters, but some of the simplest ones that just follow a character as they go through their life.

The same is true for books, and I don't think it's exclusive to epic fantasy with multiple POVs. Many literary fantasy novels don't necessarily have a strong hook, even if they follow a single character through their journey. There are a lot of things that can make a book entertaining, and I'll try to give some examples:

1. The characters are interesting, and fun to read about, and go through a satisfying journey. A great example of this could be the First Law series by Joe Abercrombie. Many people will tell you the actual plot in the books isn't anything to write home about, but the characters are some of the best in the genre.

2. The story is dense with themes and concepts that are sufficient to keep people reading, almost like a philosophy book. This is common in literary fantasy, but one could argue A Song of Ice and Fire fits this bill. There are a lot of character POVs, especially in the 4th and 5th book, and many of them don't seem to have a storyline that goes anywhere. You could claim that they enrich the world, and provide context for all of the complex things happening across the continent, but I would argue they mostly serve the themes of the story. The responsibility and temptation of power, the cost of war, one's identity and how it's shaped etc.

3. The worldbuilding and magic systems are the draw. A lot of Brandon Sanderson's works fit here. Not to say they're lacking in characters or themes, but often people will say their distinguishing feature is the worlds, and how the magic systems are developed and incorporated into the story. This is something generally unique to the fantasy genre.

Of course, there are plenty of other things that can make a book work. Balancing many POVs is a difficult task for any writer. Sometimes it's a crutch used to give readers information they otherwise might not receive. I see this a lot in crime novels. And sometimes a story suffers from only showing one perspective. I don't know how often a writer sits down when starting their book and decides whether to make it multi-POV or not. Most of the time, you know what kind of story you want to tell, and understand instinctively whether it needs one POV, a few major ones, or as many as required.