Would global warming really be so bad?

Sure, that could be negative in some areas for some reasons, but it would also be beneficial in other areas for other reasons. Suppose for example that Antarctica, or at least parts of it, would become habitable due to a warmer climate, wouldn’t that be a good thing that could possibly outweigh possible problems elsewhere?

So what is there to say that the pre-industrial era climate is really the optimal climate? That the benefits of a possible warmer climates wouldn’t outweigh the disadvantages? I have asked that many times to Al Gore supporters and either gotten no answer at all, or some list of alleged (and exaggerated) disadvantages that completely overlooked the benefits.