We experience reality filtered through our senses and our own concept of "self," which is an incredibly limited view of the world. Imagine being able to see/experience a less filtered version of reality, if only for a short period of time.
Or imagine expanding the frequencies of visible light you can see. That alone could certainly be a catalyst to change your perspective on many things.
It's not so much "losing control" as it is "losing unconscious bias." Loss of control is not the goal.
It's also one of those things that you have to experience to understand, and even then, sober you won't completely understand.
But done right, these experiences can be incredibly important to people. If it's not for you, fine, but it's funny how many people with zero experience with these substances think there can't be anything worthwhile there.