I know the creators want to get away from the whole Angel thing, but the truth is that they were bringing people back from the dead all the time. Someone gets shot or beat up and Castiel just healed them. Castiel died at least twice and Sam and Dean have been to heaven and back again.
The have had personal conversations with Death and even tried to bind him once. Dean had the chance to be a reaper for a day, yada, yada, yada. During the war between angels and demons, death was an inconvenience. We are now supposed to believe that with the Leviathans and Castiel being dead, that death has some new deeper meaning.
Don't you think that Sam and Dean could just summon an angel and have them bring back Joe, Bobby and anyone else that died? With the angels trying to defeat Lucifer, don't you think they could have increased the ranks in the field with their Dad and countless others?
I know the writers want us to forget that there is an upheaval in heaven and to focus on the new problem, but I just can't grasp the concept that for the Winchesters death is a permanent situation. With so many characters dying and coming back, I have a hard time having the depth of feeling for Bobby's death.