His motivation becomes whatever the writer currently on the book makes it out to be really. There have certainly been significantly lamer characters who have had successful series all to themselves simply due to the skills of a solid writer.
As far as returning from death, it is an age old device used in comics from the very beginning. It isn't realistic or reasonable to assume that any character is safe from a return from death. Heck, the old joke used to be that only Bucky and Uncle Ben stay dead in comics. Right or wrong, it is and always has been utilized in the medium. The only thing that has changed in that regards is the "finality" device used in killing characters off. Significantly less ambiguous.
Yes and no. Resurrections are certainly nothing new, but there had generally been a difference between "end of story deaths" (i.e., Dr. Doom caught in an explosion) and "there's a body so he really is dead" deaths. Admittedly, there was the occasional exception (Prof Xavier, Jean Grey and Wonder Man come to mind), but it seemed like there at least used to be an understanding of which characters had been retired (Mar-Vell, Bucky, Barry Allen, Kraven, Norman Osborn, etc.) and which merely put on the shelf (Superman, Dr. Doom, etc.).
It wasn't until the last decade and a half or so that all dead characters became fair game. Honestly, based on what Marvel's been putting out lately, I wouldn't be surprised if Joe Q was consciously trying to resurrect as many of the dead characters as possible. I know the legend says that Bucky was resurrected because Brubaker came up with such an awesome story, but the opportunity to do so was offered to Bob Morales as an apology for cancelling his "Steve Rogers as President" storyline, so it's not like they hadn't been looking for a way by that point.
I can see why - more properties to play with that way - but as someone who generally prefers to see old stories left along, I'm not a fan of the practice. (To be fair to the Kraven example, it's not like they retconned anything. But at the same time that's two Spider-villains brought back via mystical resurrection, which seems inappropriate for the series.)