Hi Stefan,

I agree with what David has to say; I too believe that there are a lot more
users expecting the minibuffer prompt to be intangible.

For now, I need to add the below to my emacs config (as I don't set the
customize variables using the GUI approach, and I would like to simply
append stuff to whatever the default value is):

(let (;; (get ..)                   -> ((quote (read-only t face
minibuffer-prompt)))
      ;; (car (get ..))             -> (quote (read-only t face
minibuffer-prompt))
      ;; (cdr (car (get ..)))       -> ((read-only t face
minibuffer-prompt))
      ;; (car (cdr (car (get ..)))) -> (read-only t face minibuffer-prompt)
      (default (car (cdr (car (get 'minibuffer-prompt-properties
'standard-value)))))
      (dont-touch-prompt-prop '(cursor-intangible t)))
  ;; When `cursor-intangible' property is detected in
`minibuffer-prompt-properties',
  ;; `cursor-intangible-mode' is automatically added to
`minibuffer-setup-hook'
  ;; (see cus-start.el).
  (custom-set-variables '(minibuffer-prompt-properties
                          (append default dont-touch-prompt-prop)
                          nil nil "Make the minibuffer prompt
intangible.")))

It is helpful that the minibuffer-setup-hook is updated automatically. But
I would also vote for '(cursor-intangible t) to be part of the default
value of minibuffer-prompt-properties. That way majority of the users would
see the minibuffer prompt behaving as they expect.