Terrorism + Buildings of the 1970s

I was curious over this question. Why do buildings, especially shopping centres built in the 1970s have a huge fleet of stairs to its 1st storey, which is way high above ground? There are several observations which I derived after asking some of my colleagues.

1) Because Singapore has serious flooding problems, area tends to flood when there is a heavy thunder storm( there is no proper drainage during that time) <-- provided by a colleague

2) Shopping centres want to create a grand entrance for its patrons, could be related back to the colonial times (City Hall). <-- provided by colleague

3) Due to site conditions, could be on a higher terrain, or they wanted to create natural ventilation for the basement. <-- provided by colleague

4) A deterrent to terrorism; if terrorists wants to create a 'jihad' using vehicles, they may choose to ramp into the 1st storey if it is of the same height level. Take note that during that time, Singapore was facing threats from communists terrorists. According to MHA, terrorism had occurred even before Singapore's independence. A bomb planted by terrorists took place in Mcdonald house in 1965 Singapore.

I felt ridiculed when my colleagues laughed at me when I told them it was terrorism. They said they never heard before, they mentioned it was simply "layman". Another colleague of mine "slapped" with a comment, "NONSENSE, you watched too much channel 8!!!"

Just because I sprout in Mandarin and Hokkien sometimes does not mean I am ignorant. I felt I do not really belong to these group of jokers sometimes. What they heard is filtered news by the Government and media, have they really thought through of what is the true story behind? Take a look at all those shopping centres built in the 1970s, Shaw Tower, Tanjong Katong Shopping Centre, they are similar in the way they are constructed, a fleet of stairs to the entrance, not handicap friendly.

Could anyone agree more to this?