Many "public APIs" are launched with well, very "public" intent--to extend the reach of the brand and platform. Many of these APIs are setup to pull data, enabling developers to use it in their applications for free or paid, with the understanding they’ll properly attribute the source.
Many of these APIs like Amazon E-Commerce, eBay, Google Places and Foursquare are engineered to publicly extend the central platform, all feeding back back to the “mother ship”, either through linking or other type of attribution.
As the Internet evolves, and the era of "big data" takes hold, and as the need for processing data and deriving meaning out of the flood of data available to us online grows--so does the demand for API access that isn’t marketing centric.
As a big data developer I may be comparing product pricing from Amazon to auctions on eBay, and I may need to use Google Places data to identify best places to sell my products, and Foursquare to identify local demand. The needs of big data API developers are going to be radically different than maybe your originally intended developer audience.
Hopefully you are already carefully targeting your developers and grouping them by their usage patterns. Have you identified any users that are actively using your APIs, but not necessarily following regular patterns? Have you reached out to them?
It might be the case that your API won’t be of interest to big data developers or quite possibly that this isn’t a market you're interested in. However it is a question every API owner should ask--is my API big data ready?