Hey Carl,
You liked the tree better with the volumonous rootspread because it adheres to artistry! ;-) The reason is that the trunks have only a slight taper - they have little or no taper for much of their rise AND in addition to this, the canopy of the tree is large.
In order to balance this - to make is pleasing to the human eye, the root spread has to be larger than is "normal" to both distract from the lack of rapid taper in the trunks and to balance out the voluminous canopy on top of them. Without the big root carapace, the canopy is too big.
Art, not nature! ;-)
Oh, and "nebari" (as well as all Japanese nouns) is both singular and plural. One nebari, four nebari. ;-)
Kind regards,
Andy Rutledge
b u n j i n | d e s i g n ::
www.bunjindesign.com
zone 8, Texas