because as someone said life isn't fair. and also richelle needed a problem like all books have a dilemma in them, something goes wrong and thats what the story focuses on. books arnt meant to be someones perfect life and so this seemed like the most suitable thing to do in her mind. as other said i do believe that he will come back, she cant be mean enough to put use through him actually dying!! but who knows it might be like one of those books with out the perfect happy ending everyone expected. but with the idea of spirit uses being able to turn them back to moroi or dhampir makes me think that that will happen to him. it not going to be like lissa walks up to him and boom, it will be hard i think and might only happen at the end when nearly all hope is gone but i think iyt will happen. hope i helped :)

Because it isn't possible for Dimitri and Rose to be together, without the story being dumb and totally boring.

BECAUSE LIFE ISNT FAIR

It would have made the story too predictable if that didn't happen.

DONT LOSE HOPE I DONT THINK RICHELLE MEAD WILL LEAVE IT AS HE STAYS STRIGOI THINK ABOUT IT ITS A FANTASY BOOK AND THERES LIKE ALL THE SPIRIT MAGIC AND STUFF MAYBE LISSA WILL DICOVER A NEW POWER LIKE SHE HAS THE POWER TO TURN STRIGOI BACK TO THERE ORIGINAL SELVES

IT WAS SO SAD!!!, i hope rose finds a way 2 turn him bac, but there are 6 books in total(Richelle Mead said she would right more on her web site)

Richelle Mead did it because without Dimitri turning Strigoi, she wouldn't have had a story to continue. Vampire Academy would have to end at 3.

so rose can realise she's in love with adrian!!!! then there could be a love triangle between a strgoi a moroi and a dhampir
damn that would be cool!!!
or richelle was on drugs when she wrote that
lol just kidding

it's part of the story