If you have been reading a comic for a long time, if you have been loving it for a long time, then you are emotionally invested in it. And if you are emotionally invested in something, you can't easily ditch it and move on when it goes So Bad It's Horrible, there is going to be at least some amount of regret and bitterness.
It doesn't help at all that Marvel has been extremely hostile and outright insulting to fans about this, and that their reason for making the comic go bad in the first place is ludicrous ("You want Spidey to stay married? Next you'll want him to grow old and die!", and the idea that the average comic book reader would identify perfectly with a 30-year-old immature loser who can't get any and who can't keep a job and who still lives with his aunt). That kind of attitude can easily turn regret and bitterness into anger.