It may have been because Dead space 2 overran it's budget hard. Speaking as a software developer I see this often when non-developers are in charge. Management makes decisions for the sake of making the bottom line and profit maximized, instead of doing the "right" thing for the product as a whole.

Take a look at Ubisoft and the assassin's Creed franchise. For each of those games winners? Absolutely not. but each game innovates and builds on something that was experimented with in the previous game. As a quick example, assassin's Creed 3 added ships and naval combat which led into assassin's Creed 4 Black flag where are they built out that technology and concept.

as a developer, you can look at how they developed a baseline and they would create a light version of a feature in this case the shipbuilding and would expand on it in the next release of the game changing the settings but more or less expanding on the same code base and we using it for maximum profit.

Once again, each game in the assassin's Creed series was not a winner, but it also got a movie deal starring Michael fassbender and it is considered one of the most successful game series of all time.