If I was still an FB developer I'd be enraged that Facebook would require me to pay a stupid fee just to get this priority placement, especially if my app was high quality.
Facebook should be taking the best apps and highlighting them as a service to their users. Developers of quality apps are adding value to Facebook, and now they have to pay a fee for that? Ridiculous.
They provide a ton of services for free: auth+auth, a data store, etc. They also don't have any obligation to you. You don't NEED to create a Facebook application. Simply because you are providing value to their users, doesn't mean they owe you these services.
In fact, chances are that you are providing significantly more value to your own organization than you'd ever be providing to Facebook. In that light, it seems quite reasonable for them to charge you however they please.
Add that to the fact that some people are estimating the facebook app industry to be making over $100 mil, while facebook itself still has trouble trying to moneterize, which is all conducive to facebook (legitimately in my opinion) charging app devs for a smiley face sticker.
But that also opens up an interesting business model for facebook: build the platform for users to use for free, then charge developers to use your platform to get access to the users. They could even go for a flat percentage of the app revenue.
Facebook should be taking the best apps and highlighting them as a service to their users. Developers of quality apps are adding value to Facebook, and now they have to pay a fee for that? Ridiculous.