The same reason worlds fair showed tech that will be coming out in 5-10 years. Its' fun, it's cool. It also show they are thinking long term and not quarterly
GM's "Futurama" of 1939 looked to the world of 1960.
Futurama is widely held to have first introduced the general American public to the concept of a network of expressways connecting the nation.
Bel Geddes assumed that the automobile would be the same type of carrier and still the most common means of transportation in 1960, albeit with increased vehicle use and traffic lanes also capable of much higher speeds.
To meet these assumptions, four general ideas for improvement were incorporated into the exhibition showcase.
First, that each section of road be designed to receive greater capacity of traffic. Second, that traffic moving in one direction could be in complete isolation to traffic moving in any other. Third, segregating traffic by subdividing towns and cities into certain units that restrict traffic and allow pedestrians to predominate. And fourth, consequent traffic control for predetermined maximum and minimum speeds.
Through this, the exhibition was designed to inspire greater public enthusiasm and support for the constructive work and planning by engineers and public officials who had contributed so much toward improvement of streets and highways.
For 30 years the Burma-Shave signs delivered about 30 seconds of entertainment with no significant changes in the size of the signs or their spacing. That says volumes about the enormous investment in infrastructure that Bel Geddes was proposing and the political will needed to make it happen,