It could certainly do with it, though they try from time to time with things like Onslaught or House of M, but it never quite seems to work out.
Now, obviously, a certain suspension of disbelief is needed for comic books, but when it gets to the point where nothing is set in stone for these characters, it sort of destroys the point. Whenever you are told something definite about a character, you know full well it is only definite until it is no longer needed by the Great God Plot Device. Jean Grey/Phoenix is a classic example of this, a character that they keep killing, but can't quite bring themselves to remove her entirely for fear of impacting the X-Men franchise too heavily, so she's kept loitering in the wings.
When it gets to the point when even the characters in the books themselves treat the death of team-mates as a kind of penalty box, where people go for a few issues before it emerging they didn't die for whatever reason, the story loses any real dramatic impact.
I understand these are just modern 're-imaginings' of classic Greek/Nordic mythology, but Orpheus can only travel down the Styx so many times before it gets repetitive.
