No one here works for Apple.
We are all just Apple customers/users here, just like you!
No one here can answer for what Apple does or doesn't do with their products
It is what it is and this screenshot sound has been this way for many years!
Take your screenshot sound issues up with Apple support, if you have an issue with the current UI features.
You are free and welcome to submit feedback about this issue to Apple.
This is only one of the few ways to directly contact Apple about ANY product issues.
iPad Feedback
http://www.apple.com/feedback/ipad.html
Cognizant Apple employees read ALL feedback generated from all of the various feedback pages and transfers the data to the proper and responsible Apple teams and personnel, but NO Apple employees will ever respond with any type of direct, individual replies from the feedback you post.
The more users that post product feedback about any product issue, the faster Apple, in California, is made aware and starts working on a fix/solution for a future software update.
Also, I suggest contacting/reaching out to Apple Product support and services.
Tap on the first link below and scroll down some to get to the Apple Product Support section and phone numbers for your location/region.
https://www.apple.com/contact/
OR
https://support.apple.com/en-us/HT201232
If you need to, if initial 1st tier Apple customer support is of no help to you, you can calmly ask to have this issue escalated up to more responsible, senior level Apple customer support employees to see if they can come up with other possible advice/solutions to this iPad screenshot sound issues, but I make no guarantees, whatsoever.
If need be, you can have your iPad issues escalated all the way up the chain to Apple engineering level customer phone support.
Even if no acceptable resolution, Apple, AT LEAST, logs all support calls and issues.
Best of Luck to You!