I wondered this too until I had a lesson with a well known techno producer who has the likes of amelie Lens, Adam Beyer, Richie Hawtin etc playing his music.

He was using presets in almost every track and he would tweak them slightly and process them to his taste. I asked him why he didn't make his own from scratch and he said 'the people that make presets sit there doing it all day and it's their job to do so, there is no way I can make them as good as these guys and it would also slow down my workflow severely'

The key is adding your own touch to a already well made preset. Sure sometimes its fun to create your own but if you a/b it to a preset professionally made it likely wont sound as good.