Juri Linkov <address@hidden> seems to think that:
Yes, I use to say that they should be in the Edit menu every time we
discuss this ... ;-)
Seriously, they are very useful and I see no reason not to put them
there. And `occur' and `multi-occur' should be there too, of course.
There are lots of commands that are "worth putting in the menu" if we
judge by their usefulness. But if we put them all in the menu it will
be so big it is inconvenient to use. So arguing that "this command is
worth including" is not a good way to think about the question.
The menu is not necessarily flat. Using submenus it would be possible
to organize most useful commands in a convenient way. For instance,
the "Search" menu could have submenus "Search files" for the grep family
of commands, and "Search buffers" for the occur family of commands.
A better option is that the menu item might just be "find". Instead
of a singular minibuffer prompt to a specific grep command, a buffer
explaining different grep options could be provided. The cursor lands
on a text widget, and then the users types in the expression, and then
choses the right type of grep/find command from a selection of
buttons. An expert Emacs user would, of course, just type M-x
my-favorite-grep-command RET, but for a new user, this would cover all
the bases in one menu item.