Since cartoons don't rely on human actors at all, it's easy for animators to go wild about how they design every element in these shows, from the characters up to the background. Of course, that also includes scenes of sexual nature and lots of it! And by an adult, it doesn't mean that the plot of these shows is now aimed for the more mature audiences, but it simply means that you'll see a lot of stuff that you will never see in regular animated cartoons and shows. Now, given the popularity of such animated cartoons and shows, it's not really surprising that some animation studios decide to put out adult-themed material aimed for those who just can't stop watching them. What matters is that you're enjoying what you're watching and that no one else can stop you from watching those animated cartoons and shows even if you're all grown up already. It's fun to watch, even if the plot doesn't seem to make sense most of the time. You just can't shake off your love for seeing beautifully drawn art in the form of characters, backgrounds, and other background elements. And there's also a big chance that you still love watching those kinds of shows even as of today.
Admit it, you were addicted to watching cartoons and other animated shows back when you were younger.