Chaincases are a geography thing. They work in in the climate of Northern Europe as their Northern European designers intended. Going out in the cycling world over the last century through the Commonwealth and one finds British style bikes in Australia, but mostly minus their chaincases. It's relatively warmer and drier there than back in England. India? Once again, British style bikes, but few chaincases. Chaincases tend to collect and retain water inside during monsoon season.

BTW, there have been a couple of bikes misleadingly advertised with chaincases in N.A. over the last few years (Electra Amsterdam, Trek Cocoa, etc.) that actually have fancy chainguards, completely open on the back (LH) side.