I think it's a combination of the perceived lack of value (too many people view "tons 'o' minis" as an essential part of boardgame kickstarters), combined with bad timing. Marvel Champions is just now hitting stores, and offers a surprisingly similar sounding experience at first glance.
Both games let you mix and match a variety of components to make a variety of gameplay combinations. In both games task the heroes with attempting to defeat the primary villain who is trying to complete a scheme. And in both games, the villain can bring additional goons, minions and game effects into play to make life difficult for the heroes.
Granted, there are plenty of differences as well; more hero customization in MC, along with secret identities, more positional gameplay and villain/scheme variety in HoN, etc.. Still, there are some clear similarities, except one game uses already popular characters and is available now, while the tother one won't be out until next year. I just have to wonder if that's how some potential buyers are looking at it.
Personally, I think there's enough differences between them that any fan of superhero games will enjoy them both. I've already backed HoN; I have a lot of faith in the Sandler brothers, and this looks like it's combining all the best parts of Street Masters and Brook City, with some cool new twists thrown into the mix. And I just picked up Marvel Champions, and I'm having a blast with it. I think both of them will exist nicely in my collection.
