Continuity mistake: When Samuel L. Jackson is grabbed by the shark (CGI) blood splatters all over the place. In the next shot the place and the water are spotless.
Continuity mistake: Carter puts a bandage on his right arm because of the blood. When he tries to shot the shark the bandage gets larger.
Other mistake: Near the beginning of the film, Carter asks Tom how high the fences are, then he tells them to make them higher, and Scoggs confirmed they were raised, but you can see that the fences never get any higher.
Revealing mistake: As one of the lab crew is showing Tomas Jane the suspended tiger shark you can see a horizontal line in the water in the background. this is the edge of the water tank used to film the exterior scenes (mentioned in DVD extras).
Answer: They viewed her as a villain because it was her research that backfired and caused all of the chaos, even though none of it was intentional and it was a mistake. But audiences can be ruthless and unforgiving at times. However, the ending did feel like a cheap cop-out that created more plot holes. And many do feel she should have survived and completed her character arc. I don't know why they never offered the ending as a bonus feature on the DVD, but fans started a petition on the Change site calling for Warner to release the original ending. Thomas Jane is on board as well, as he's promoting it on his Instagram account. So that's probably the best way to get Warner's attention if you want to see the original ending.