For me, it is a reason to not upgrade to a 15Pro.
I love the old physical silent switch and use it several times a day. What I will miss:
I can FEEL if it's on or off in the dark or when the phone is in my pocket.
I can SEE if it's on or of when looking at it, without having to unlock the screen to check (or how else can the on/off status be verified?)
When having the action button instead, and I BELIEVE it's off, and press it to turn it on, but then it was on anyway, will it then be off, so I have to press again to turn it on, as originally planned?
If Apple had spent more effort on e.g. making the tap on the back feature working better and more versatile, and left the old switch alone, this would have been a much better option, imho.