These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Values Dissonance: The reason Solomon trapped these characters in the brass vessel in the first place? No, not inflicting torments on other creatures or the like (as was the case in the earlier "Testament of Solomon"), at least not as noted. No, according to the Lesser Key's entry on Belial, "Solomon did this because of their pride, for he never declared other reason why he thus bound them." To many of us, that's kind of excessive (especially when psychos like Andras and Glasya could easily have been doing much worse than strutting, but they only get booked for pride?). However, given the Hellenic references (the zodiac signs are a dead giveaway), the intent was likely that the Goetics were guilty of hubris. Combine that with Yhwh's insistence that no honor or glory be rendered unto any supernatural entity besides himself and... well...
Some of the demons have Ascended Demon aspirations, deliberately being benevolent as a means of redemption (even if Focalor's idea of "benevolent" could use some alteration). Apparently, they're deluded in their wishes, because God doesn't want to redeem them... or, depending on the theologian, can't redeem them because there's no way to create someone who could properly offer blood atonement for each demon like Jesus could for humanity. This point crops up in St. Anselm of Canterbury's Cur Deus Homo?—justice is integral to God's being, so he can't commit injustice even against himself, which is what would happen if he let anyone who'd committed a sin in without having been cleared with proper blood atonement.note Which ignores several Old Testament instances
But God's omnipotent, therefore if he doesn't want to do something, it's because he doesn't want to do something.
It's also worth noting that the various conjuration litanies in the Ars Goetia basically deem a spirit "good" or "evil" not on what they specifically do, but merely whether or not they're obedient ("good" if they obey the summons with all due haste, "wicked" if not and there's reason to believe it's not because they're busy helping other conjurors). This extends to the aerial spirits from the Ars Theurgia Goetia, as well. If they're typically "loving and obedient", they're Good. If they're typically disobedient and/or deceitful, they're Evil. Effectively, the Key of Solomon and other grimoires operate on a Lawful Neutral view of the world taken to its ultimate conclusion—"Good" is just another word for "Lawful", "Evil" just another word for "Chaotic".