Why is only jmp434 doing this? If this forum had 4 more guya like him the whole game would be done by now! It needs to be done, Squares remake is going to suck anyway when it arrives in the year 2045.
It's interest.
There are a number of us in the forums, some who model for a hobby, and some of us who do it professionally, I'd guess at probably around 10 in total, but its based on interest.
Some of the artists might be more interested in redoing FF8's backgrounds, or redoing FF9's, or the areas they were interested in doing have already been done and they don't want to go to the effort of remaking the entire scene 100%.
Much the same reason people don't do the environments in order, or leave some unfinished, interest, thats all it boils down to really.