because it won't have a happy ending
Oh for goodness sake, go read 1984 and then tell me the book is rubbish because it doesn't have a happy ending.
If all films/books etc have to have a happy ending then you immediately write off the idea that any situation is remotely powerful or scary.
Like in 28 Days Later I really thought they all should have died, because there was no easy way to get around what was going on.
Or in Equilibrium (which rips off 1984 to say the least) he should have failed.