In the sense that we need to remove our dependence on a single-point-of-failure planet to avoid existential risk, then I agree that terraforming is ultimately desirable.
But entire planets claimed by crushingly authoritarian political systems or uncontrolled profit-seeking corporations doesn't seem like a great way to safeguard humanity either.
Primarily avoiding the single point of failure. Extremely secondarily, to create a diversity of human cultures, because I think that will ultimately create a bunch of things people enjoy (better art etc.).
But entire planets claimed by crushingly authoritarian political systems or uncontrolled profit-seeking corporations doesn't seem like a great way to safeguard humanity either.
What do you want terraforming for?