After all, "M-x" is easy enough to type when the Alt
key is Meta, and Alt being Meta is rather desirable.
Is it not better to follow the standard for Gnome and other platforms where
it is possible? Does not Alt beeing META clash with these? Would it not be
better to have Alt as META as an option? Could not that be good for both new
and old users?
This is not decided by Emacs. If both Alt and Meta are available, Emacs
does distinguish between them. It's only if Meta is not available that
Emacs treats Alt as Meta.
Given that some apps use Meta (e.g. Emacs) while others use Alt but
a vanishingly small number use both, I prefer to configure xmodmap so as to
only have one of the two, in order to remove this gratuitous distinction.