Because they like him, and they don't like her. The story... or glrorified snuff film, that is broly's movie matters, that story matters or rather the fighting maters to people, That's what endeared them to him, and his multiple appearances over the years. No one is claiming story does not matter. What i'm saying how he got here, to a great many people don't matter.
They like what he did, they like what he can do, and they like the vibe that comes off him. They like when he claims to be a god or a demon, they like his crazed screaming his mind god mad with powers destroying his memories focusing his rage on an undeserving target, they like his design, they like what he's about.
That's why.
And that's why kale exists, because they couldn't have that in the main series. So they just made another one. But in the instance they could have broly... they will just want broly. And heck a lot of folks might not like kale in the first place.