People became accustomed to rooting for the main character to mindlessly defeat hordes of monsters like an arcade game. People wanted to see Ripley and Hicks blazing machine guns on xenomorphs for three hours with some romantic ending. Rather than Hicks and Newt dying like nothing and Ripley being infected with only hope of suicide.
Deviating slightly from the game discussion, but I don't really think this is a fair way to describe it.
In Alien, you had a small group of unarmed people trapped with the alien, and one person survived.
In Aliens, you had a team of trained, heavily armed and equipped marines engaging an alien hive... and three people survived. One of them seriously wounded.
But they absolutely didn't "mindlessly defeat hoards of monsters like an arcade game". To quote Hicks, "we just got our asses kicked, pal". In every engagement save Ripley's encounter with the queen, the xenomorphs either won, or were using it as a deliberate faint.
There was more action, but it didn't really accomplish much more .
...
To loop it back around to Dead Space... In the Alien franchise, the message (which is reinforced with almost all follow-up media, like comics and such) is that fighting xenos is a losing proposition. The best you can hope for is for some degree of survival, at a high cost. You never "win". You just lose less.
But the xenos never win in such an overwhelming way as to effectively end the story, either. Even if a protagonist dies, it's a big galaxy, and the xenos are a swarm of locusts, not an angry god. There's a point in fighting. The xenos will make you pay a heavy cost, but the end of humanity isn't in the cards.
The Brethren Moon in Dead Space screwed with the formula. They're just a game-over event in the way that xenomorphs never can be. They were as close to being a literal angry god as you can come without invoking an actual divinity.
Basically, the Brethren Moon made the entirety of the first three games (minus the Awakened content for 3) pointless, because Awakened basically gave you the middle finger and pointed out that everything you did was futile. You were always going to lose. There was never any hope. Even if you stopped Convergence, the best you could do was very slightly delay Armageddon, because there were countless Brethren Moon and they were coming for you.
As a game design and storytelling issue, you can get away with "Haha, it didn't matter, you were fated to lose from the start" as a plot twist in a single game. You can't get away with it in a trilogy (almost a tetralogy, counting Awakened) where you've become massively invested in the storyline. People react... badly. See also: Mass Effect.
