I don’t think the show ever claimed for it to be a utopia, but they have no homelessness, hunger, etc. at least on Earth and member worlds. That doesn’t mean there isn’t that outside the Federation or on distant colonies which tend to be left to their own devices. For instance, Tasha Yar’s homeworld was a failed colony. We don’t know at what point it failed or if/when the Federation stepped in.

If the Borg behaved like the hive-mind from Pluribus - friendly but compelled to assimilate (“Everyone is happy here, we promise”) - I think that would have been a lot more interesting in the same way it makes Pluribus so interesting