Ashura's death really is bizarre. On one hand, he shouldn't have been alive after taking an explosion to the face after he was already in critical condition against Kaido, but then Oda never comes back to him, and we're left wondering. Then to just hit us with "oh, he's actually dead." It's such a weird sequence of events for One Piece, considering the "good characters" are always given a send off of sorts. Izo was a little better, since he essentially sacrificed himself for Kiku and Kin, and Oda provided him that last stand.