expanding CC list for opinions ... (personally I'm ok with that change)

This is a personal setting and can be changed by the user its self
within ~/.inputrc. Our bash reads both /etc/inputrc and ~/.inputrc.
The default is an active acoustic bell and we should not change that.

Werner: I'm fine with adding it to /etc/skel/.inputrc as well, point is that the beeping is quite annoying and everybody I know turns it off. 

Hmmm ... then you're knowing one person which do not turn off the bell.
Just do an echo

      echo 'set bell-style none' > ~/.inputrc

ok, there is always one person wanting the bell sound :) still I'm not sure if its a sensible default. some other distros switched to a visible bell instead, to only annoy the local user and not all the other office mates at the same time. 

Hmmm ... the bell is used very seldom if I type and edit my command line.
Only if I use BackSpace to often or the history up/down reached the
end the bell rings which is IMHO OK.

Btw: You may use

       xset b off

for an xsession.  Beside this I'm using

       xset b 50 400 100

which is OK for me.

it beeps when pressing <tab> twice in a row, which I use frequently to find the right completion. 

You may use also

  set show-all-if-ambiguous on
  set show-all-if-unmodified on

all those "xset" features do not work under KDE unfortunately ...

not even Konsole->Settings->Notifications "Bell emitted" is the one ...

but: Kcontrol->Sound->SystemNotification->"Something special happened"
is the sound that is emitted on every "\a". Unfortunately there seems
no way to control the volume of these sounds.
(and clicking on "Player Settings" will always show "No audio output",
 which seems wrong with all that noise ...)

Beside this the readline library knows about:

       show-all-if-ambiguous (Off)
              This  alters  the  default behavior of the completion functions.
              If set to on, words which have more than one possible completion
              cause  the  matches  to be listed immediately instead of ringing
              the bell.
       show-all-if-unmodified (Off)
              This alters the default behavior of the completion functions  in
              a fashion similar to show-all-if-ambiguous.  If set to on, words
              which have more than one possible completion without any  possi-
              ble  partial  completion (the possible completions don't share a
              common prefix)  cause  the  matches  to  be  listed  immediately
              instead of ringing the bell.

Therefore you may try out

   echo 'set show-all-if-unmodified on' >> ~/.inputrc

and/or

   echo 'set show-all-if-ambiguous on' >> ~/.inputrc

Ruediger: konsole/settings/Bell/None works for me for disabling the annoying beeping, but that disables it everywhere (also in vim, less and other apps). 

ok, set show-all-if-ambiguous on seems to work without beeping. 

testcase: 

mkdir tmp/valgrind
mkdir tmp/valgrind-3.1
cd 
cd tmp/valgri<tab><tab>


any setting that makes it stop beeping here is fine for me. 

Created attachment 72743 [details]
/etc/skel/.inputrc

An example ~/.inputrc suitable for /etc/skel/
of the aaa_skel.

added the attachment to aaa_skel
(fixing the typo: one of the two show-all-if-ambiguous
 needs to be show-all-if-unmodified)