They wanted to be able to do the whole "OMG! Will she die!?!" thing. *nods* Because they are evil. The 'how' rather than the 'will'.

Aw, I'm pretty happy that you didn't hate Rose. I shall make a good faith attempt not to hate whoever it is that they have set up as next season's companion (if it would just be Jack, this would be so much easier). Also, if I should rewatch tGitF soon, I'll try to ignore the emotional discontinity with the rest of the series and just pretend that it's a really short, kinda sappy movie, as I do like somewhat sappy movies.