I doubt anyone will be dumb enough to let to happen a second time.
Have you actually watched any of the Alien movies? They've done it. They keep doing it. Anytime Ripley's name pops up or there is some sign of the Xenomorphs, somebody goes and tries to collect samples, tries to bring them back home. "Crew expendable." The people in charge of these projects don't care about the humans involved. They want the weapon, and they
will try as many times as it takes to get what they want.
I meant on a large scale where more than a handful of people know about it.
Let's take a look at the sequence of event for a second: *deep breath* In the first film, besides the handful of suits that issued those orders, all anyone outside the Nostromo knew is that a commercial towing vehicle inexplicably dropped off the grid and never made it home. The only ones that would even care would be the family of the crew and like an old ship lost at sea they would probably have just been told it was most likely a malfunction or some natural disaster. When Ripley turned up decades later, nobody in the company from back then was probably still alive evenand I doubt they left a post-it note for their successors saying "P.S. We sent a bunch of space truckers to an alien derelict and probably got them all killed."
The only one who even half believed her story was Burke who took it upon himself to send a prospecting team out to a grid reference. Now admittedly at this point somebody higher up clearly took notice as the colony suddenly went dark and authorised the deployment of a starship with a dozen marines. Remember that if anyone other than Burke believed in Ripley's xenomorph story, all they knew is that a bunch of untrained and unarmed commercial pilots and engineers stumbled onto something nasty and it got all but one killed. So if the same thing had happened to a remote colony (only 160 odd people remember) then a dozen heavily armed marines could handle it and perhaps a properly equipped team could look at this purported derelict once the colony had been dealt with.
Now remember that Burke was acting apparantly on his own, his superiors in the company probably didn't know what he'd done and most just thought it was only a down transmitter. When they arrive and it all goes to hell then Burke, again takes it on himself to infect Newt and Ripley to smuggle the organisms past ICC quarantine. If there had been some massive conspiracy back home then this wouldn't have been necessary. He was betting he could use those samples as leverage to get himself off the hook for sending the initial order (assuming he hadn't covered his tracks already) and set himself up for life.
Once THAT all went pear shaped then clearly a lot more people at Weyland Yutani and probably the military as the Solaco transmits it's logs. So when Fury 161 is infected, they go in loaded for bear (or rather, "loaded for xeno") and could probably have bagged the thing. When they lost that and it was clear the derelict was destroyed (I think Cameron's script mentions it was destroyed in a lava flow) then the whole thing was filed away and mostly forgotten. TWO CENTURIES later, someone, somewhere, somehow, for some reason dusted off the old files that included Ripley's blood samples and decided it'd be worth a go, with the proper precautions.
Based on what they knew of these things, they were very careful. The only thing they didn't anticipate was the degree of intelligence and communication they possessed, which enabled them to stage a break-out. Again though, this was a black project, out in unregulated space and "not approved by congress." So not exactly well known. Even when the Auriga was destroyed it had probably taken everyone who knew about the project with them, except perhaps for some General or another, assuming they weren't on that base the ship came hurtling down on.
Now let's review events; so far we have, at most, a few hundred dead from this thing, spread over two and a half centuries: 6 on the Nostromo, 160-odd colonists, 12 or so marines, 25 convicts + 3 custodians & Ripley and however many didn't escape the Auriga.
While I realise it's hardly a fair measrure, statistically speaking more people die in freak accidents in a year than these things kill in a century. On top of that, to the human race at large, these things don't exist. If any stories ever leaked out it'd probably be regarded on a similar level as the Roswell Crash or the Philadelphia Experiment. Plenty of stories and conspiracy theories but very little actual evidence and not taken very seriously by most people.
Of course, if a whole planet became infected then that all changes. Until that point, the greatest strength the xenos had while dealing with humans was that nobody other than a handful of greedy businessmen or foolish Generals even knew they existed. If on the other hand they start nesting in the sewers of a major city somewhere, then the cat is out of the bag and the gloves are off.
No General or corporation, no matter how profit driven or ambitious would fail to appreciate the immediate danger if these things actually got loose and did some serious damage in a civilian population. Worse case scenario, they loose a planet and most of the population, maybe in the millions. After that, there's no denying these things exist or how they should be dealt with. There may be some additional "outbreaks" but there's no way they could threaten the entire human race. Just like in a lot of zombie apocalypse fiction, at a certain point, people will get over the initial shock, draw a line in the sand and
adapt.
Even in that theoretical scenario, I can't see Ripley-8 giving a crap either way.