Presently SW allows these settings for justify:
a) Last line left aligned (very reasonable default!)
b) Last line justified (looks frequently very odd, but for god sake)
c) If there is only one word in a line, expand the whitespace between the
letters in such a way, that the first letter is at the beginning of the line and
the last letter at the end of the line.

I would like to see these settings:
1. Inter-word spacing:   Reduced maximal by [0·0em]  Extended maximal by
[1em|Auto|None]
2. Intra-word spacing:   Reduced maximal by [0·0em]  Extended maximal by
[0·2em|Auto|None]

Per default the inter-word spacing should at least 3 times wider than the
intra-word spacing. Frequently "0" is the best for inner-word spacing. Setting
these values very tight (0) turns of justify, but using reasonable values, the
text will look better.

3. Protruding characters: [None|Punctuation]
(For details see URL, page 23 bottom to 29)
"Punctuation" lets the ;:.,- characters hang a bit over the right border. This
makes the text better (the right border looks smoother since the grey value of
the page is more constant).
In ConTeXt (see URL)  for punctuation it is defined as (left border hang, right
border hang):
! (0 %,20 %), ' (0 %, 70 %), ` (70%, 0%), ( (5%, 0%), ) (0%, 5%), ´ (0%, 70%), -
(0%, 70%), , (0%, 70%), . (0%, 70%), : (0%., 50%), ; (0%, 50%).
&emdash; (long ---)     0%, 30%
&endash;  (medium --)  0%, 20%
quotes of the (99/66: ,, `` ´´) type 50%, 50%