
My sentiments exactly, Spidey.
I won't keep you in suspense about my feelings - this was an utterly stupid move that an editorial department which obviously does not have a clue foisted upon us.
In all of the message boards and letter columns that I have read, there was no groundswell for Aunt May to return. None. And there's a good reason for that. The simple fact is - Aunt May was a one-note character whose sole purpose was to fret about Peter, and in turn, be someone he could fret about. Back in 1962, when Spider-Man debuted, superheroes did not typically have family responsibilities. They came and went as they pleased.
Peter Parker, therefore, was different, which made him unique and contributed to his popularity. His life, like the lives of most of us, was a juggling act. He had to balance his superhero exploits with the need to take care of a loved one, as well as school, work, etc. And, it was ironic, and more often than not, humorous, that the brave, strong superhero was treated like a frail, helpless child by his loved one. Adding to the irony was the fact that May feared and loathed Spider-Man, while (supposedly) never suspecting that he and the person she loved more than anything else in the world were one and the same.
Fine - but as the years went by - nothing changed. May always got sick ( I should go back and count how many heart attacks or near heart attacks she had), Peter always got frantic, always had to be in two places at once, and this plot device got old real quick. When, in Amazing Spider-Man #195, Peter received a note that Aunt May had died in the nursing home, I was personally hoping that she really was dead (another illustration of the bankruptcy of the Marvel editorial staff - faking May's death had already been done before).
In an interview, former (and one of the best) Spider-writer Roger Stern indicated that whenever he mentioned to the public that he was writing Spider-Man, he was frequently asked "Is Aunt May dead yet?" Translation: she was a nuisance. Stern and some of the other writers tried to give her a purpose by having her run and old folks halfway house, and fleshed out her background a little bit, including a youthful romance with a gangster, but this did little to make May a useful, viable character.
Part of the problem was simply that Peter grew up. He was 15 when he became Spider-Man, and at that time he needed his Aunt May. However, as the years passed by, he got a job, moved out of the house, went to college, graduated, and got married, like most of us. And even if he hadn't married (a concession to the MJ-haters out there), he couldn't have stayed 15 forever anyway. May's purpose had played out.
Oddly enough, the one thing that could have given May a new lease on life was her revelation just before her "death" in Amazing Spider-Man #400 that she knew that her beloved nephew was Spider-Man. She had known for years, but was in denial because of the fear of losing him. It may perfect sense, actually, and as May herself said "I'd have been an idiot not to know." In this moment, May was redeemed as a character because it was apparent that she was not as stupid or senile as she had long been presented. Had she lived beyond that point, it would have opened up an entirely new avenue of stories, and her and Peter's relationship would have irrevocably changed, and so would May's and MJ's.
But, they let her die, and it was a wonderful story as Peter had to come to grips with what all of us must face if we have not already - the death of a parent.

But, in hindsight, it's apparent that this was just part of a larger picture that was playing out in Marvel's attempt to completely revise the Spider-Man titles. This, of course, but the botched "Clone Saga" in which it was initially revealed that Peter had actually been a clone since Amazing #150 and that Ben Reilly, the drifter who had returned to town, was the real Spider-Man. May's death was only part of that revision.
But, as we all know now, the Clone Saga was a disaster, and Marvel had to reverse gears and bring Peter back as the true Spider-Man, which necessitated bringing back Norman Osborn, the original Green Goblin, since the whole scheme had taken on such a large and absurd nature that Osborn was the only villain who could conceivably have pulled it off.
So, while sales of the Spider-titles bounced back to their pre-clone saga levels, they were still in the dumps relative to how well they used to be, and it apparently never occurred to Marvel that overexposure, poor writing, and the changing nature of the comics industry (much in the same way that the Big Three networks no longer dominate television the way they once did, Marvel and DC no longer had a stranglehold on the comics business) were to blame.
So, the solution became to close the current storyline, "re-boot" the titles (cancelling two along the way) and bring Aunt May back. The reasons were alledgedly "because we'd lost more than we'd gained," or that "because she's a reminder of why Peter puts on the Spider-Man costume every day" (Direct quotes from Howard Mackie, the current Spider-writer). None of this tells me exactly what Marvel felt was lost. I for one, did not miss May, and I suspect I was far from alone.
Anyway, the device used to bring May back, that the Green Goblin had replaced her with a genetically altered actress who he told Spider-Man's secret identity to, was just plain stupid. Not only that, but it should have compromised Spider-Man's secret identity. Was May was proven to be back along the living and her "death" a scheme of the Green Goblin, wouldn't someone, anyone have wondered what use a frail old woman was to the Goblin? And then, wouldn't someone remember that the same Green Goblin murdered Gwen Stacy, again, someone he theoretically he should have no use for? And then, wouldn't someone realize the one thing the two women had in common - Peter Parker. But then, everyone is an idiot in comic-book land, and Marvel must have though its readers were as stupid as its characters can be.
And what has May done in the first year of the re-boot? Nothing. Well, sorry, she did get a new hairdo. And it wasn't long before in Peter Parker: Spider-Man Volume 2, Number 2, while trying to save New York, Peter forgets May's medicine and panics over it. And once again, we are subjected to May's anti-spider-Man diatribes, supposedly now reinforced by John Bryne's buchery of Spidey's origin where the Burglar invades the Parker home looking for Spider-Man.
And you know what? Sales aren't any better.