I'll give you my perspective, as someone who loves these movies to death.
For me, it's a combination of tone, action, and execution. The action is genuinely impressive when you think about the choreography and variety (I know you said to you it's a lot of pistol shooting, which it is, but there's a lot more variation than that. Shotguns, car action, swords and knives, nunchucks, bows and arrows, etc.). John Wick pretty much set a new standard for action movies now, and they've built upon that since the first movie came out in 2014. People are just genuinely excited to see good action play out on screen.
I get the criticism about the repetitiveness of the action. I definitely felt it with Chapter 3 towards the end. And I'm not gonna pretend like the story or characters are super well-written or anything. But I love how it looks, how it flows. The cinematography in this newest one is honestly the best in my opinion, and I'm a sucker for the overall tone of the series.