What is the significance of LIX15? Why did NSE see the need to have a separate basket?

LIX 15 Index is designed to provide exposure to the liquid stocks while making the index easily replicable and tradable,

source: http://www.nseindia.com/products/content/equities/indices/LIX_15.htm

LIX15 is almost close to one third of nifty and cosists of only 15 liquid stocks from CNX 100.