I don't think that killing Dumbledore was as much killing off the wise old wizard mentor/leader as much as it was killing the one person that Harry could unfailingly count on. With his parents dead, with Sirius dead, with Dumbledore dead, Harry is (for the first time since he found out that he was a wizard) entirely alone. True, he has the Weasleys -- who have seven of their own children to worry about and Ron and Hermione -- but Dumbledore was the last parental figure that he had to call his own.

Ron and Hermione are his own age and cannot be expected to take care of Harry in crisis. Not that James, Lilly, Sirius and Dumbledore haven't done their parts ten-fold, of course, but Harry (at sixteen) is still too young to have to deal with that. Clearly obvious, and probably the main reason why Voldemort wanted Dumbledore dead.

Agreed with resurrection and the improbability of it, though sharya brings up that Dumbledore's return is necessary in order to prove Snape innocent. I'm not sure how the portrait thing works, so I don't know whether that would be the prime solution. That's why the phoenix thing makes sense to me, because I've always also thought that it is highly improbably for Dumbledore not to have an animagus of his very own.

Someone else made the point that Harry is going to need to forgive Snape and Voldemort in order to defeat Voldemort. This point was made in response to my claims that Harry and Voldemort both needed to die in order for the series to end satisfactorily.

I think I just want Harry to die, though.

Weasley is our king. (http://www.knight2king.net/Knight2King/weasleyisourking.html)