For me, I've just never found the flappy paddles to be engaging in the same way as an actual clutch and shift lever.
It comes down to the fact that when I've owned cars with flappy paddles (incl. my current), I operate the car in automatic mode 99% of the time. In fact, since buying it in February I've driven my car in Sport mode several times, but I've never actually done the paddles. So I don't feel like I'm "in tune" with the sound, the feel, and everything else involved in shifting a manual. Whereas every manual I've owned, because it's in manual 100% of the time, all of that is second nature, and so I instinctively know where I am in the power band at all times, know by the position of the shift lever whether I'm in an odd or even gear (and based on speed/etc I know which gear), etc.
Flappy paddles feel more like driving a video game car to me. I don't have the same level of feedback that I get from a manual.
And don't get me wrong... If I had a car that could ONLY be operated with the paddles and not in automatic mode, I'm sure that would become second nature the same way it does with a manual shifter. But since it's not my daily drive mode, I don't feel like I could get used to it well enough to use it for the fun driving.
So I'm sure the paddles would be great if I used them enough to make using them second nature. But today, I just don't. They're pointless to use in around-town / commute driving. That's the point where driving an automatic is fine. But that also means I'm unfamiliar enough with them that if I wanted to run through a canyon, I don't know the car well enough in that mode to excel.