Though nothing is perhaps "objectively" good or bad, for humans many things are good or bad, often in a practical sense.
I'd be hard-pressed to tell someone who's currently starving or suicidally depressed for instance that they're not suffering.
The question then is whether there exists more of this kind of suffering in the world than there does its antithesis and whether the suffering might somehow be worthwhile in the end.
The answer that philosophical pessimism gives is, "no".
The answers of other philosophies may be different.
However, I would argue that other philosophies tend to view the world through a rose-colored lens of optimism and of assigning meaning to things which ultimately have none.
In my opinion, nihilism, pessimism, and antinatalism are the only ones that go far enough, so as to destroy the deep-rooted illusions which we are brought up with in this world, so that we may view it in a more objective way.
Whether this makes one feel good or bad is irrelevant.
I did not choose these views because I like them. I chose them because they make more sense than any competing views.