On the other hand, delivering a desktop application is about equally difficult for 200 customers or 2000 customers, so the Macaw guys should just revel in their extra cash (aside from the stretch goals that they chose to take on as well, and printing a handful of extra t-shirts).
Due to some "Mythical man month" reasons adding more people and features can put you in quagmire easily unless you have very good project managers. I am not sure even those could bear the influx of order of magnitude more money than needed.
Kickstarters are not preorders.
Anyone aware of the realities of software development enough to think about capping the max should be aware of the mythical man month and cognizant enough to realize they can just bank that extra money as a rainy day fund for when the product almost certainly goes over schedule even with the original plan (Hofstadter's law).