There is no direct benefit for everyone, just to avoid last minute manipulation as we had seen many many times, KLCI suddenly shoot up 5-6 points in last minute. It is just for the closing price more accurate reflecting the situation.

Sometimes a stock for the whole day trade at 10.00 then last minute with 1 lot done (due to no seller queueing) then the 1 lot done at 10.30 which eventually the closing price become 10.30 and index being calculated with 30 cents rise.
If one didn't monitor the market one, simply look at newspaper reporting, you will think: oh, great my stock up 30 cents today, in fact, it is just because of 1 lot being done.  
Or someone didn't monitor the market one, then see the closing price is 10.30, then next day, straight away call the remiser to buy at 10.30, in fact, it falls back to 10.00 or 10.10 next day then person is being 'cheated' by the closing price already.

This situation particular pronounce on some low liquuidity stocks even on some blue chips stocks like Petgas, BAT etc whereby there is not many queue between sellers and buyers also.