"Father's Day" Doctor Who Episode

I have recently watched the Doctor Who episode "Father's Day". Time travel plays a big part in the plot line of the episode. The Doctor and Rose go back to the day that Rose's dad dies. Before the car can hit her dad, Rose saves her dad. Saving her dad messed up the timeline of all time. Since that has happened, some creatures, called Reapers, have come and eat people. If they want the Reapers to go away, they must repair the timeline of all time. But before they can do that, the Doctor gets eaten by a Reaper. But before he is eaten, he tells Rose not to hold her past self, this would create a paradox. She holds herself anyway, thus making the Reapers come and eat the Doctor. Rose's dad realizes that he must die in order to make Time right. He goes and is hit by a car that was supposed to kill him in the first place. The car was stuck in that time because it needed to hit her dad in order to move on. Rose goes by his side and watches him die. This is very depressing but it makes the Reapers disappear and the timeline is restored. What I have noticed in all the time travel short stories, tv shows, and movies is that people go back in time and make one small change and the future ends up not how it was before. So the people go back and fix it making everything better in the past, present, and future. I wonder why this occurs often in time travel entertainment pieces. You could do a lot more than doing the same thing over and over in different movies, tv shows, etc. Why not trying to travel to the future and bring a person back? How would that affect the present? The future? Time travel is more than traveling back, so why not make movies about traveling to the future? They could be as equally good or maybe even better than the ones about traveling to the past. 'Til next post!