The observation is that people tend to use them primarily for text-only mail.
My *hypothesis* is that the real inhibiting factor is the problems
involved in sending mail to people who are not known to use the same
multimedia system. If my hypothesis is correct, then a mandatory
With the understanding that reasoning by analogy is always risky,
people have sent paper mail to each other for many years, indeed
centuries. It is, and has been, about as easy to include little
drawings, photographs, etc., in the envelopes with such messages, and to
use elaborate illumination and calligraphy in the text as to have "plain
text" messages. However, in the overwhelming number of cases -- at
least in most cultures -- people (to use language consistent with
Nathaniel's understatement) "tend to use...primarily... text-only"
forms, and to do so with rather conventional choices of fonts and
Alternate hypothesis: regardless of the transport mechanism, fancy
mail really isn't important enough for the vast majority of messages to
be worth the marginal trouble.
Note that this doesn't suggest the minority is unimportant, or that
there are not cases within that minority that are consistent with
Nathaniel's hypothesis, but I would expect that most messages are
unstructured plain text today and will be unstructured plain text (in
some character set) five years from now. That guess is plus or minus
"canned" fancy multimedia "signature files", which could easily become a
fad, for at least a while.