Its actually used alot, if you want to make a screen print you need to press 2 buttons at the same time the power + the touch.
And it needs to be held very long before the iphone powers off.
As far as i know there is no function on the short pressing the power button, at least nothing happens on my phone.
So i disagree also about the case theory, all cases i ever saw have the power button free as its one of the most important buttons so again a non argument.
They have/had no reason not to put touch id back into the iphone for any generation they released, they simply want to FORCE people to use their new toy the face-id.
Because i learned now that they started using after apple removed the touch id, yes i asked all my friends and i asked also why they do not pay with face-id it takes too long and is a hassle todo. Its not simply press a "button" like touch id you have to open it then need to id yourself and guess what it does not really work on ideal terminals as fast as touch id. so that is why they do not use it to pay its much more handle the phone before you can pay and fails often.
Also remember apple loves collecting all data they can on you and they go through great lenghts todo so, if you believe they would not store your data then stop dreaming.
Because they do the exact same as M$ or G$ which actually collects everything you do, by that i mean REALLY everything you do.
Why else would it constant send a steady stream of data, did one of you use a data tracker to see what is all send from you devices towards apple ... my guess is in 99% NOPE.
How often is something safed onto the icloud did you ever check... i think most never check besides the ones with limited data contracts.
I admit on the phone its less than the M$ and G$ sends but still alot is saved on icloud and that is easy to tap into for apple.
They actually have to give access to the different country security forces if they demand to see the data as well.
That alone tells you that they have full access no matter what.... But in general they mostly collect when and how late you pee and if you bark to the phone or not

.
I am not gonna tell what is collected or not, i worked for a super large phone company so i leave it to your vision/thoughts what they do collect or not.
Those special forces can access all data they want almost everywhere, only the countries who do not like the USA and friends try to block them. Like china, russia, and so on.
So no matter what companies tell you they always have access to your data, no matter what or where.
The only way to not share data is not use a SMART phone which is sharing everything you do with the makers, by that i mean all the other smart phones on the planet.
Anyway long story short there is no reason why apple did remove the touch other than forcing people to use the face toy, as i learned from all my friends non of them used it ever.. after the removal of the touch they had no choice < period >
PS smart tv act the same way especially if they have microphone and camera build in to collect even more, or if you have the smart home toys from Am$ and G$. i hope you understood my steno company names because they tell you exact what they do with your data... if you guessed it right one bonus point if not try again and send me your data so i can see what answer i need to give you on that topic.
It big business including the smart watch which actually collect tons of medical data as well, and you give it away for free, super smart from these giants... They actually know your probably gonna die sooner than you yourself or your doctors.