We must travel to distant planets, it is no secret at this point. The closest such planet is Mars, and it is very promising. The main problem is, Mars is very inhabitable. No water, no trees, very little atmosphere, the easiest way to fix it is to terraform Mars. This has its fair share of problems though, both good and bad.
Mars is very inhabitable, and terraforming it will help make it much more. Terraforming Mars will help us breath better, get possibly sustainable water, and will make the experience much more smoothly as if it were on Earth. Terraforming seems like a no-brainer, but it has many problems.
Some say terraforming Mars is a bad thing, because we are disturbing the natural surroundings. There might have been other organisms that we would never know existed if we terraformed over it. One of the main goals of traveling to Mars is to see whether there are actual creatures there. Many say it is unscientific and unethical.
Others say that it defies another major factor of what we are trying to do. It will make Mars habitable. This is a problem because another major thing we are trying to accomplish is to see if Mars CAN support life. So if we terraform it, we will never know because it will practically become Earth. Terraforming Mars will ruin some of our main goals of going there in the first place.
In conclusion, terraforming Mars has its upsides and downsides. It will make Mars much more habitable. It will also probably kill any remaining organisms. It will also be like playing on easy mode, and we will never know if Mars itself can be inhabited. It is all up to personal preference and much more scientific research.