The problem is in number 2, as many applications try to be os independent (or at least unix-flavor
This is the point that most people don't seem to grasp and perhaps why Linus was so harsh: Emacs
works on a large number of unixes, why is a breakage on Linux the fault of Emacs? Sure it may be
bug, but that would make it a bug that exists outside of Linux and the main purpose of Linux is and
was to be a independent unix-like posix compatible operation system.
This also means that probably Emacs (by virtue of it being a widely used application) was just first
to be impacted by this behavior. And since other applications are probably also directly impacted by
this change of semantics (read: effective ABI change) is not desirable.
The KDE bug is different in that there is a clear indication that it would also not work on other
unixes and probably went unnoticed due to different defaults in distributing KDE which caused that
part to be hardly used (or perhaps some ports has a local patch to fix it which never got upstream).