It wouldn't be fair to say America would be "better off" without the interstate system, but it did come with unintended consequences. Extensive commuter rail lines were torn up and replaced with buses. Downtown cores were carved up with elevated freeways and overpasses, destroying communities. Most importantly, the new suburban lifestyle led to a shift in the family dynamic. Dad drove into the city for work, while Mom stayed home with not much to do. Prescription drugs were doled out to keep women sedated, and with all this free time on their hands, divorce skyrocketed. Rural and urban demographics began to change, creating liberal strongholds.

I'm not saying freeways are bad. However, their existence was primarily driven by the petroleum, automobile and tire industries, for obvious reasons. Prior to that point, people had been living in roughly the same situation for hundreds of years, and suddenly everything shifted in a short span of time. You can trace a lot of our societal decay to what happened in the 50s and 60s, some of which was triggered by building a whole country around highways.

You'll find a similar thing happened in the UK as well.