In the long run the damage to Native American society was for the best. If it wasn't Columbus at that point it would have been someone else at another point. The other nations were going to take over at some point no matter what. Native Americans weren't built to survive the influx.
Even if Columbus did not come to the new world, someone else from Europe would have. It is also clear that if China had wanted to come to the new world, they had the capability to do so. It was inevitable that the new and old worlds would come into contact in the end. Columbus should not be blamed.
Progress is hard to stop, therefore I believe the arrival of Christopher Columbus (although he really wasn't the first one here) to the New World was worth the damage it wreaked on the native society. The problem with this, is the fact that if Christopher Columbus wouldn't have done it, someone else would have. Given the European and world climate at the time, it was inevitable that the native society would have been harmed, regardless of the original origin of the new settlers.
Yes, the arrival of Christopher Columbus' ships in the New world was worth the damage it wreaked on Native American society, because more diversity in a culture is always a good thing. Columbus and his people learned to work well with the native people. In some ways their life was better, but in other ways, their life was worse. There is always a trade off.
Christopher Columbus is not really the cause of imperialism as much as others who later came to the New World. However, I would argue that of course it wasn't worth it to the native peoples of what later became the United States. An entire culture was decimated as the U.S. continued to grow, expand, and force native peoples out from their homeland. Of course, it was worth it to those who settled in the United States, but at huge cost to another culture that had more right to the land than the new settlers believed.