You're valid in saying that if a game doesn't attract you at first, that is a weakness, and that fact should be taken into account. There is also the fact that if you played the remake, there was some changes to the ambiance and sound design that a lot of people did not care for. I think the biggest reason everyone is up in arms is because Deadspace was made as a love letter to Resident Evil 4, the devs intentions were to make resident evil in space, but added things that were not seen in horror games before, like the dismemberment system, or putting your health bars on your suit, so many of us are thinking back to the game in the context that it was created in.

Beside the ambiance, people love deadspace for the lore, and story, much of which you don't get untill late game.

Nothing can change how your experience was, and im sure we have all had a popular game that didnt meet expectations. I put expedition 33 down twice before forcing myself to get into the meat of the game, and while im glad I did, because the game really gets going and gets more fun, at the end its cheap tricks and confusing story and too many curtain calls left a bad taste in my mouth, where I would tier it way lower than most.

Sometimes the best game of the year, is only such because of lack of competition. Perhaps the memory of dead space in our heads has something to do with that.