Thanks for the invitation to argue (and thank you and the devs for grml, btw) :)

So based on the responses I have to base my argument on (1) _size_ occupied by
the programs and (2) "too many", roughly that "10" options provides too many
choices (3) many of the expendable wms are "not properly configured". Finally
(4) some comments about the linked removal of software in your list.

(1) program size
----------------

- : 12 kb
evilwm          --
dwm             --
w9wm            ---
ratpoison       -----------
jwm             -----------
twm             ------------
wmii*           -------------
openbox*        ------------------------
awesome*        --------------------------
fvwm2           --------------------------------------------------------------
pekwm           ------------------------------------------------------------------
fluxbox*       
------------------------------------------------------------------------------------------------------------

The above is a graphic representation of the size of the installed binaries with
the scale topmost. Now the real quantity of interest is of course the size of
the binary, docs, dependencies as compressed and stored on the GRML iso. Some of
the appropriate figures are provided in this thread but not for all the wms,
however there is a correspondence and the real quanties make the case even
stronger and I'll include it as an appendix.
  The "*" above marks those wms mooted for inclusion and basically shows the
fallacious logic if program _size_ is the issue: "to save space let's remove
thosethat occupy the least space and retain the largest non-tiling manager and
two largest tiling managers". To re-phrase: "Let's save space by removing those
wms that save the most space".

(2) "too many"
--------------
Okay, let's just assume that "about 10" is "too many", based say on a one-to-one
correspondence with our fingers and that "4" is a decent-sized number. Then of
those 4 a user has a choice of 2 tiling and 2 non-tiling wms. So great? Not
really. I don't really know what criteria were used to filter out those four wms
but if there were any they could be better. For eg. a "user of text tools"
usually has one problem: competing keybindings. Gnu screen overcomes this by
having an escapable, configurable escape key, and so does ratpoison. The only
other _general_ solution is to use a mouse and menus -- but this is the only
type of wm presented amongst the 4 *wms -- a bit strange for a distro aimed at
"users of text tools". Those of us who want to run X, a terminal multiplexer and
still have _all_ our keybindings available for zsh, emacs, vim etc are left
choiceless.
Anyway, take another look at the chart above to see that "1" can be "too many"
when that one is fluxbox and "3" "not too many" when the three are evilwm, dwm
and w9wm.

(3) wms "not properly configured"
---------------------------------
Here let me first say that I really like the default grml configuration for zsh,
screen, vim etc. But generally, in the absence of "your" configuration files,
and particularly for wms, it is better to have a vanilla configuration. Just
swap the .emacs files of two hackers if you want proof.

(4) linked software removal
---------------------------
ratmenu is a general menu that works well with ratpoison; it can be used with
any window manager. Linking it to removal of ratpoison is the same as removing pd
menu with dwm because it has a "d" in common.
dwm-tools I think has now become suckless-tools and may be a requirement for
wmii. dmenu may be included in that package and again it too is used by people
who aren't necessarily running dwm. Other people (than me) will know better
about the suckless software.

Appendix (1) program size
-------------------------
Keep:
 fluxbox                       1300
 fvwm2                         746
 openbox                       292
 wm-ng (is just a simple wrapper script to start fluxbox with gkrellm and
desktop icons)
Considered for removal:
 dwm           180             28
 evilwm        94              24
 fvwm          14700           746
 fvwm2-crystal 5104
 jwm           299             135
 pekwm         1253            792
 twm           397             149
 w9wm          127             36
Further discuss keep/removal of:
 awesome 2785 + 446            309
 rapoison 528                  128
 wmii 401                      159

The first numeric column (provided by Mika) appears to be the appropriate size
(in kb) while the the second numeric column is the size (in kb) of the installed
binary (grml2009.10).