The evidence for plate tectonics is so strong that it would be delusional not to believe in Pangaea.
I don’t think there’s any way to judge whether the world would be “better or worse.” We might be able to say how things would be different.
For example, the position of the continents has shaped the evolution of life. The reason Australia has so many unique marsupials (kangeroos, koala, etc) is because Australia is separated from the other continents. On the rest of the world, placental mammals dominate. If Australia was connected to the other continents, it wouldn’t have such a vastly different set of animals.
Human culture would probably evolve on a different trajectory, too. In the real world, humans didn’t spread out too evenly, largely because the continents are separated. A few humans trickled from Asia into the Americas about 10,000–20,000 years ago, and their descendents quickly became a wave of settlers, the native Americans. Their culture developed separately from European/Asian/African culture. Then, thousands of years later, a trickle of Europeans came to the Americas, which then became a wave that completely engulfed the native American cultures. If all the continents were connected, such sudden migration events (and cultural takeovers) might not have happened. Cultures may have developed and engulfed each other more gradually.