Although I am a native New Yorker, I don't have any personal stake in whether the NYC Marathon goes on this Sunday or not. Except for seeing bits of it on TV, I've always been pretty oblivious to it. I've never been stuck in traffic because of it; I've never had to clean up after it. Nor do I run a business that benefits from it, nor am I a fan who follows the sport.
The controversy over Bloomberg's decision feels weird, maybe because I am so detached from the event both as a tradition and as a practical matter.
I've seen arguments that New Yorkers need the Marathon to run as scheduled to "send a message" of some kind. I don't see the value of any such message, and I'm not sure who we're sending it to.
I've read that the Marathon will bring much-needed money into the city ($340 million), while not really diverting all that much in terms of resources that are needed elsewhere like police and medical personnel. If it is all about money, I can see how it would be hard politically to just say so, although Bloomberg seems to have pretty much done just that.
I've seen counterarguments that letting the race go on is insensitive and disruptive to many people who are suffering, especially in Staten Island, which was hit very hard and is where the race begins. I see from the course map (PDF) that the runners will barely spend any time in Staten Island. On the other hand, setting up the starting line will be a major, perhaps disruptive, logistical undertaking. And as is often the case, maybe it's the idea of the thing that really matters more than the numbers.
I don't have a cogent argument either way. All I can say is, it feels weird to me that the Marathon was not canceled. I can certainly understand the strong feelings of the people who condemn Bloomberg's decision. But maybe there are valid reasons for this particular show to go on.