Well, IMHO, I would not object to the use of the term, seaweed green,
if you also included a corresponding Munsell designation - which I
can choose to use or ignore.  I find it much easier to go to my
Munsell to get a useful estimate (sic) of the color than to travel to
the coast where I am likely to pick up a brown seaweed or in certain
times of the year some decidedly reddish algae.
 
There is a pervasive problem with typological thinking - the ease and
convenience of it outweighing precise and accurate
communication of data.  We could also employ estimates, such
as, some, a few, a lot, instead of taking the time to count the
sherds and present frequency or percentage tables - likewise deadly
dull reading which takes up space and breaks up a narratiave.  After
all, the number of sherds is often a function of breakage rather than
the actual number of vessels represented.
 
Types, whether used for classifying artifacts or estimating color
values are based on the assumption that the mean of a population is
more importance than its variance.  Maybe, but not a priori.  If
there is variance of color, then I would find maximum/minimum values
more meaningful - and probably more precise and accurate, if for no
other reason than the selection of a mean color is itself quite
arbitrary and may not be the mean color value at all.
 
I suppose the question comes down to the relative importance of the
convenience to the analyst compared to the degree of objectivity,
precision and accuracy in what is communicated to the reader.
If the goal is to simplify complex data for, say, the non-professional
reader, then a host of Munsell numbers is deadly dull, useless, etc.
Ofttimes it is entirely appropriate to be "not scientific". On the
other hand, if the reader is a professional interested in issues of
quality control (e.g. homogeneity versus variability)
of a ceramic technique compared through space and/or time,
then lumping all variation into a simplifying term, like seaweed
green, obscures vital information.
 
You should object if I criticize you for not providing data to a
reader you never intended to address your work to.  I would
object, in this case, if you suggested that your work was
adequate for my needs and alleged it was my fault for not finding
your work useful.
 
Cheers,
 
Irv Rovner