Why was `transient-mark-mode' turned off for `delete-selection-mode'?

[Drew Adams <drew.adams@oracle.com>]

I came across this item in NEWS:

** Delete Selection mode can now be used without Transient Mark mode.

"Can now be"?  That sounds positive, as if we are adding some new
possibility that is useful.  Are we?

Why would we do this - what is the use case?  Why should
`delete-selection-mode' no longer enable transient-mark-mode'?

Have we had requests from users who turn off `transient-mark-mode',
asking to be able to use `delete-selection-mode' without seeing
the selection?

I've searched a bit for a discussion about this, in emacs-devel and
in the bug list, but I didn't find anything related.  I searched around
the time of the change, which was apparently made on 2013-12-11, with
this commit:
http://bzr.savannah.gnu.org/lh/emacs/trunk/revision/115459

Stefan Monnier2013-12-11 14:42:34
Revision ID: monnier@iro.umontreal.ca-20131211144234-evm5nwt04uoggorp
* lisp/delsel.el (delete-selection-mode): Don't enable transient-mark-mode.
(delete-selection-helper): Make sure yank starts at the top of the
deleted region.
(minibuffer-keyboard-quit): Use region-active-p.

So far, this change doesn't sound like a very good idea to me, but I
would like to know more about it, in particular the rationale for it.  

Delete selection mode has always been about providing similar
delete/replace-the-selection behavior to what is prevalent outside
Emacs. Why would we now divorce this behavior from highlighting of
the selection?