Because all the OTHER major means of generating electricity can be sited according to the needs of the grid. Nuclear can be sited virtually anywhere (albeit less cheaply as one might be forced to use reactor-to-air cooling rather than reactor-to-water).
You can't move a geothermal site. Even solar is much better than geothermal with respect to "location, location, location".
"b) Why can fossil and nuclear plants exist at remote (+300 miles) from major urban areas w/o problem?"
You're the one fixated on +300 miles as "remote". I consider 300 miles or so to be reasonably "nearby". "Remote" is >700 miles (the length of the longest single transmssion line in the world). Why do you think I'm talking about California vs. Maine, or the region West of the Mississippi vs. the region east of the Mississippi?
The only way geothermal can contribute in a significant way is if technology develops super-conducting transmission of electricity, or if there is a shift from the "electric grid" to the "hydrogen economy" to overcome the problems of transmission losses. Fundamental physics will NOT be denied.
Geysers is 150 miles from SF.
Steamboat is 30 miles from Reno, 175 from SF.
You are all wet on this one. Bye.