why is there carpet on the floors (in the airport and train) and cloth seats on the train!
The Metro in the Washington, DC area, of similar vintage, has similar amenities— and issues. Transit ridership had been imploding, so planners wanted to build "modern" systems that addressed everything people said they hated or feared about the subway. Escalators, air conditioning, food and drink bans, suburban stations with ample parking, video surveillance, and public art naturally coincided with carpet, which reduces noise and slipperiness, and comfy chairs to make the experience less clinical.
In practice, of course, money, engineering, management skills, and so on didn't always match plans, and the key to increasing ridership was not gum-free platforms as much as it was increasing the price of gas and increasing commute times caused by rising volumes of road traffic.