Why are comics afraid to make major changes?

Comics seem to be constantly tossing out these huge shocking storylines and then wanting to undo them. The ultimate bait and switch. Sticking with Spider-man since that's the name of the group, here's a few examples:

1. Doc Ock dies...but is resurrected by the Hand 2. Aunt May dies 3. Norman Osborn dies 4. Mary Jane 'dies' 5. Mary Jane gets pregnant and the baby just vanishes

The only major change to Peter's life they stuck with was his marriage to MJ, and now they are trying to even undo that! The thing is, all of these changes could have stayed without ruining Spidey. In fact, the stories are hurt much more by always returning to the status quo IMO.

I'm anxious to see if they have the guts to keep Mysterio dead even though that happenend in Daredevil.

Comics are afraid to make changes because there are always a cluster of 'hardcore' fans who want to keep everything the way it was, change is bad it signals the end of an old era and they are afraid of what the new era offers... personally I'm all for changes, as long as they are well handled and the editors have the balls to stand by it...

I'm pleasantly surprised with what JMS is doing with Spidey at the moment, not the best of changes that could've been made but its quite a significant change, and nothing too earth shattering that will totally piss off Spidey-Purists... It's been a long time since I was actually proud to openly admit to being a Spiderman fan. But thanks to the new wave of creators (JMS, Romita Jnr, Jenkins, Bucky, Benids and Bagley) the prides just pouring all over me baby, yeah!

I'm sure we will see him in U.S. since that book is starting the whole story over again, which means no one is dead........................as of yet.

Mac the rejuvinated