The west is the industrial hub of Singapore, where jobs are visibly created. The east is where the night life is, where the way of life is more chaotic and less organized, where counter-trend ideas can flourish more easily. Low anchored himself in the east and it became synonymous with pro-opposition ground. That is why the east is more vulnerable than the west.
The centre is the hub of high finance and economic elitism. That is why PM Lee felt at home shedding those tears at Boat Quay, across the street where people make out at night and rake in the cash by day.