While trying not to get on my own personal Spidey soap-box (I was against OMD/BND and even my enjoyment of Dan Slott comics couldn't sway me), there is some information that I want to make sure isn't lost in this debate over sales for ASM.
As Paul O'Brien has chronicled in his sales figure reports for the last two years at THE BEAT website (where whatever poster who posted that sales data on Marvel.com likely got his info), you can't simply compare current ASM sales to old ASM sales. There are factors to consider in such analysis.
The first and foremost is that Spider-Man at the time had three ongoing titles, as he usually has had for many years. At the time I believe it was ASM, SS-M, and FNSM. ASM always sold the best and was considered the "flagship" Spider-Man title for obvious reasons. The rest are always secondary books, usually connected by crossovers but often doing their own thing despite starring the same hero and much of the same supporting cast. While ASM may have had over 90-100k sales for a lot of the time, the other two Spidey books usually sold maybe half that or two-thirds that. When one compares current goals for the thrice monthly ASM experiment after 2007, one has to calculate the monthly "average" from all three titles combined per month. Paul calculated that number at about 62k per issue for every "three issues a month" comic of BND ASM. In 2008 he doubted that sales would ever reach or be lower than that for issues of the thrice monthly ASM; he has been proven wrong by 2009 for some weeks.
The second fact is that when one is using old ASM sales figures, one has to remember that for a full TWO YEARS before it merged with the other Spider-Man books, it had been boosted in sales by crossovers and other events/stunts. Before ONE MORE DAY, there was BACK IN BLACK. Before that there was UNMASKED. Before that there was the CIVIL WAR crossover stuff which reached then-historic numbers for some Marvel books after the 90's. Before that were PRELUDE TO CIVIL WAR issues, with the new costume issue (Iron Spidey) getting like 2-4 printings and high sales with a Bryan Hitch cover. And before that, of course, was THE OTHER, another Spidey-crossover. My point is that you really can't gauge what a "natural" sales figure for ASM as itself was because it was ALWAYS being pumped with gimmick sales stunts for at least 24 months before Jan. 2008. Some might argue that the fact that Spider-Man so desperately needed to return to an era when his comics needed either smaller or company wide crossover event stunts to maintain high sales was itself a cause for alarm, or at least that Spider-Man had jumped one shark too many.
Sales drop offs for ASM since Jan. 2008 also can be hard to figure for a cause. It is very possible that ONE MORE DAY was a counter-productive thing that made fair-weather or non-fans excited, but longtime readers of ASM embittered (some 35k of them usually read all three separate books, after all); ancedotal evidence claims that. On the other hand, it could be simply diminishing returns; DC has learned for three years that a weekly comic doesn't always maintain high sales; TRINITY's sales are maybe a third what 52's were. A sale drop off could have nothing to do with BND but could have more to do with the market being unable to keep a Spider-Man book that is very close to weekly at high sales numbers indefinitely. Remember, as ULTIMATE proved, something can't still be "fresh and new" a year and a half later; it simply is "less new".
My personal opinion was that it would have been better to try the "3 times a month" ASM thing for a while before Joe Q sought to enact his personal editorial vendetta against the Parker marriage, because all that did was add some stigma to the new experiment from die-hard fans, which sometimes can backfire. I certainly would have loved to see Dan Slott's ideas for making the Parker marriage work. I know he had 'em. He must have. SPIDER-MAN/HUMAN TORCH, the mini that for many is still Slott's best work, had many hints of that. While any ASM sales drop offs may not be entirely due to MJ-Fan backlash, it certainly didn't create the best environment long term.
The other factor is that so far since the new ASM debuted, sales have spiked for things that are harder to predict, such as a well publicized story. And of course, 2009's sales figures will be unfairly boosted at the end of the year for the title by the Obama issue that sold over half a million copies across five printings. Some have argued that the real tragedy is that despite that issue, not even a thousand of those readers returned for the next regular issue. Hell, I don't even think 400 readers did.
My point is that while it would be great to say, "a HA! Losing the Parker marriage has resulted in lower sales for ASM!", there are other factors at play here to explain any sort of sales fluctuation. That said, I would be curious how many people read the weekly newspaper strip, whether through sales of papers that carry it or some online poll (as I am sure some people read the strip online, like many strips); if fan letter demand was really that high for a newspaper strip, it could serve as a factoid towards what the general public, who has had a 5 season 90's cartoon that has been airing in repeats on cable for a decade, and only three feature films that earned over two billion dollars worldwide, thinks of the idea of MJ being in Peter's life as a significant other.
Frankly, I see stunts like ONE MORE DAY or some of DC's Hal Jordon stuff where borderline middle aged men chase their childhoods from the 70's at the expense of any fan who has been reading since as a critical reason not only of "diminishing returns" for superhero sales figures, but also why younger readers don't bother. The fallacy of adults is they usually underestimate the collective intelligence and savvy of anyone younger. That is why network TV execs usually believe that "dumbing down" a show will appeal to kids, forgetting that as former kids themselves, their fondest memories are of shows that didn't do that to them. Most people under 21 know very well how old these characters are, and they know that many things remain unchanged since the day they were born. There is some hatred of manga, but I can tell you this; manga is quite serial and not as static on average; ONE PIECE vol. 400 will not have the EXACT same status quo as vol. 2 did maybe five-seven years ago. For American superhero comics, reversing a mere half decade of character progress is usually called a "yearly event where nothing will be the same". The very thing that gives American superhero comics their strength, the eternal endless soap, is also their greatest weakness. No one takes ARCHIE seriously, but that is one of few comics that doesn't shy away from how nothing can ever change in it's universe beyond details like new ethnic minority students at Riverdale now than even in the 90's. Laugh at NARUTO, but at least in a few years, more has changed in the manga of that than likely in many superhero books. DRAGON BALL Z is seen as male action fulfillment fantasy, but Goku, the star hero is popular with many kids under 21 despite not only being happily married, despite not only being a father, but a GRAND-FATHER. That appeals to youth, who are smart enough to know things change a little as they grow up and experience new things. If comic editors could think of the future instead of revisiting their own dusty childhoods, I think the industry would have more imagination, more innovative ideas and so forth.
But, knee-jerk shocker moves usually drive up sales. Oh, well.