Oddly, this came up twice yesterday, in discussion with different people in different organisations, which is surely a sign that it needs to be made more public: there is genuine business value in having an API, and in using it to build your own applications.
An API is valuable in its own right because it streamlines development significantly. The communication with the core development team and amount of integration code that needs to be written both drop dramatically. I’ve been in the unusual scenario where an application had to be written twice from scratch, once when there was no API and once when there was one, which makes for a good A/B test. First time around the application effort matched the integration effort. Second time around the integration effort dropped dramatically — from months to days.
But an API really comes into its own when you use it yourself, internally. For one thing it forces you to make sure it’s really usable; you will flush out a lot of issues and make it more relevant to external developers before they encounter issues themselves. For another, you can expect those integration cost savings to be reaped internally: your own developers will find it much, much easier to build on your platform, and therefore you can cut through that impossibly-long to-do list at a much slicker pace.
None of this is free of course. Like so much, it requires some kind of investment. The API won’t be right first time, so it involves learning and feedback. If you have a version 2 and are considering moving people from the old version then you need to choose between migration costs, maintenance costs, or dropping those older services.
But once you have made those investments a new world awaits. And all your problems will be… of a better class.