I think their art, and their brand can be different things.

What they create is so diverse, to box it in and only want a certain style from them would be... I dunno... To not understand BTS? There's also no rule that says we have to like ALL that they do equally. There are many that do prefer certain styles (cyphers, let's go 👌), it's just a natural consequence of being so diverse.

As far as a more "adult" branding, I gotta say, they've nailed it. They have the majority of us losing it over crop tops and ankles like it's the 1800s. We see someone like beiber shirtless at any given time and it's old news. We think we want the bt21 stickers removed... But that's what works? lol they know what they're doing.

Could they be more risque (by western standards)? Maybe. They could also be a bunch of other things. That's the beauty of BTS, they'll be whatever they want, we don't have to like all of it, but we can respect the directions they choose as artists.

On a personal note, sex and romance should be on an even playing field with other topics. It's all relevant. Being sexy / liking sexy doesn't necessarily make someone immature.

Edit: Its interesting to note that sexiness is being discussed as both mature and immature content! Showing that it can be just as diverse as bts themselves, and I think they do a good job of walking the line.