You're right that the more Alien encounters happen between 'Alien' and 'Aliens', the less sense 'Aliens' makes. You can come up with ways to explain it (which is what SM and I are trying to do), but those explanations aren't airtight and aren't going to work for everybody - 'Aliens' wasn't written with a bunch of intermediate spin-off stories in mind, after all.
Special Order 937 is about procuring a specimen, but the Company didn't know what that actually was - they were just homing in on a signal of nonhuman origin. The result of that endeavor ends up being not just a total bust, but a colossal financial loss by way of the Nostromo and its cargo.
The Nostromo's flight recorder gets recovered, giving them another lead. Meanwhile, the signal from the Derelict gets switched off. The Company literally buys a space station only to, once again, walk away with less than nothing when the station gets destroyed almost immediately after they buy it.
You can count the events of "Alien: Blackout" if you want, too, where the same thing happens all over again.
Irrespective of the increasing risk of the public or the authorities catching wind of the egregious corporate malfeasance, at one point or another the people making these kinds of decisions are going to cut their losses.
The "real" answer is that writing a narrative set in between two other narratives is hard - you have to balance having appropriate "stakes" and "revelations" to make the story interesting and justify its existence, but at the same time you risk compromising
their narratives. 'Out of the Shadows' had the same problem except that it went in the other direction. Rather than derailing 'Aliens', 'Out of the Shadows' nullified itself by having Ripley forget the whole thing. That doesn't mean it doesn't have neat characters doing neat stuff or that it's not worth experiencing, of course.