Why wargame the Russian Civil War? Well for me, it was a chance to get into a period that few were already into. The challenge of doing research and finding figures in a sparsely gamed period is constant.
Also, this an important period in the history of Russia and indeed, Europe and the west. What if the whites had won? No Stalin! What would the effect on the history of the 20th century be? Would Russian have cooperated more in 1938-1940 to stop Hitler? Would Russia have taken part in the 1939 partition of Poland? Would the Germans have overun a non-communist Russia?
The period is gaining in popularity. When I started building my army 7 years ago, everything had to be converted from WWI or earlier figures. Now you can buy ready-made RCW figures and even armored trains in 15mm, 20mm, and 25mm. Who knows what will come next?