I don't think it's the absence of character death that people think is bad, but the fact that Oda writes himself into these situations where characters are either implied to be dead or put into a situation where it is unbelievable that they would survive, and then just brings them back for no other reason than the fact that he doesn't like killing people off. Oda doesn't have to kill a character off, but don't make it seem like they are dead and then pull the carpet out from under us.
If he didn't write himself into situations like Pell or Pagaya(and even nameless fodder now with G5 surviving Smiley's petrifying gas), it wouldn't be a fandom wide rule that we know nobody dies. It kills a lot of the tension because we know Oda can't go through with a death. That's why nobody actually believes that Monet and Vergo are dead and why their "deaths" weren't as powerful as they could have been. All he would have to do is have a scene of Pell distancing himself from the bomb instead of having it go off point blank and then implying his death on a cliffhanger. Then maybe people wouldn't get so mad about it.
I personally don't really care about the lack of death. Actually, I don't particularly want any of the characters to die because I want to see more of them. But yeah, Oda could stick to his "no needless death" policy without having characters seem dead. It's almost contradictory to his reasoning of not wanting to use death as shallow grab at the emotions…