I agree. It would have been pretty cool if he lived.

Found this on AccioQuote:

Sorley Richardson for Publishing News -Why did you have to kill Sirius when it was the best thing that happened to Harry for years?

JK Rowling: We are back to me being a murderer, aren't we? People have asked me this a lot. I have been repeatedly told Sirius was my favourite character, why did he have to die? You can imagine how bad that makes me feel and in fact after I killed Sirius I went on the Internet and somehow stumbled across a fansite devoted entirely to Sirius and I killed him in the last 48 hours, so that wasn't good. I think you will realise why he had to go in terms of plot when you read the seventh book. It wasn't arbitrary although part of the answer is the one I have given before. It is more satisfying I think for the reader if the hero has to go on alone and to give him too much support makes his job too easy, sorry.

Lupin, Sirius, Moody, Dumbledore...

Yeah, she took Harry's support system, glad she left Mr. Weasley although Ik he was on her list of death too.

Yes. He was one of the best.