It shouldn't have been Dei to fight Sasuke then, Kishi should have put like ... someone apart from Deidara! lolGuys your "bringing-back-to-life-characters" complaints are pointless.
Look at me. My favourite character was killed at the beginning and you don't see me whining about it. I think that Kishi killed Sarutobi at the right time and gave one hell of a heroic death if you ask me. Same thing with Jiraiya.
For a plot to be interesting, characters have to die, even the most loved ones.
About Deidara, the fight was unfair I completly agree, but I actually wanted Sasuke to win, even if I dislike him so much. If he died by the hands of Deidara it would be freakin' ridiculous if you ask me. Put yourselves in Kishi's place and try to continue the story from that point without Sasuke. It would be lame.
In my opinion, every single character that Kishi killed, he did it in the right time and with good reasons to do so, he's an amazing writer. Even if I might feel sad for never reading about them again.
Cheers
I know that he isn't coming back to life, it's just he was the awesomest Akatsuki and I was totally crushed when he died.