Looks. I just don't like the looks of LG's UI. Or anyone's aside from vanilla for that matter.. As others have stated, the ability to customize almost any aspect of the interface is a big contributor to my love of Android. With stock launchers, I lose some of that ability. Hiding the notification bar is pretty important to me as well. Not sure why but I don't like the look of a different colored bar cluttered with icons at the top of my meticulously arranged home screen lol. Same with nav keys. I use pie. As mentioned by others, I use the 'screen off' app combined with the double tap gesture to retain the knock knock feature.
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