Security at Suntec City

I visited an office in Suntec City. They asked to scan my NRIC but as it was lost, I gave them another card with the bar code. They gave me a visitor pass, just to get through the barrier.

I do not know the purpose of recording all visitors to the offices. There must be several hundred thousand visitors to Suntec Mall every day. They are not recorded. So, what is the purpose of knowing who visits the office? How does it enhance the security of the office? If there is a bomb, it is likely to occur among the visitors to the mall.