Ughhh........
They all deploy differently. Auto (I think you mean side opening), and otf are truly one handed. That's not a gimmick that's actually helpful. Whether it's medically based like arthritic conditions or situational where one hand is already taken, an auto is fantastic.
BTW, internals of otf have really good and strong locks, which I'd trust far more over liner, frame, or back locks. Also if the lock on otf fails, you don't lose fingers.
Lastly, otf carries much thinner in the pocket, to where you don't notice it's even there. You can put a very light and thin knife together in a way that you can't with most manual folders.
So watch this video, tell me if it's still gimmicky.