This is a deeply philosophical question. But it's highly dependent on the circumstances of a particular animal's extinction. Is it ethical to resurrect the Wolly Mammoth into our current climate when it's significantly warmer than the climate of the Ice Age? Likely not.
Was a species hunted to extinction? Maybe restoring that population would ease our collective conscience to some minuet degree.
So maybe bringing back some of these species is being done so as an apologetic gesture? Perhaps out of hubris?
To be fair, we're notoriously cruel to the animals that we farm for mass food production and less directly to wild animals (when human activity destroys their habitat). Images of such farm operations might remind you of conditions imposed on alleged dissedents by dictatorial regimes. You know, those same conditions that are condemned as atrocious when imposed on humans by humans. And this kind of treatment is still absolutely prevalent today on humans and other animals.
