Without getting into "One More Day", which is a fun debate, but one I can have elsewhere, I know very clearly why I dropped Amazing Spider-Man.
The promise of impact.
I feel like Amazing Spider-Man has removed the promise to me, the reader, that the events that happen in the book will be important to the character, and through him, important to me.
This isn't the first time this has happened to me in reading comic books either. The death and rebirth of Jean Grey is probably the best example, though there are others. When the reality of "drama" is removed from a comic book, often shown through the death of a character, but not always, then I am no longer as invested in the story telling.
I understand that some people will say that they are able to just digest the new material for what it is, as fun entertainment, and that's great for them, but I don't feel the same way.
Take for example, a television series. Let's use "ER" for this example, as I think it's got a pretty good track record for maintaining it's continuity. If, this season, they had said "Doctor Greene didn't die of cancer, that was his twin brother!" then the reality of the "drama" would be challenged, and it would feel to me that the emotional investment I had made in the events surrounding the death of the character were cheated out of me, and I would feel bad about being a consumer of the television show.
So, as a reader of Spider-Man, or any comic book, for that matter, I feel that there is an unspoken deal between myself and the publisher that I will give them not only my dollars, but an emotional investment in their characters, and in return, I expect fine art and writing, and some care not to disregard the feelings that they've evoked from me previously.
That's not always the case, but I'd like to think it is.
And that is why I stopped buying Amazing Spider-Man.
Spider-Man, in challenging the reality and promised impact of the events that occur within it's pages, broke that unwritten contract with me. It suddenly said "Hey Scott, I know we told you earlier that this was important, but *sike!* it wasn't! We don't think that story we told you before was good enough, so it doesn't matter how much emotion you put into it, we're undoing it all. Hope you give us your money next month." I won't. I dropped the book, and I don't feel bad about it at all.