I've been in this position before. We wanted to open up our APIs, encourage integration with 3rd-party tools, and make our product as open as possible.
Good intentions, but the unintended consequences are significant. We expected the openness to drive more sales, improve customer satisfaction, and generate more goodwill around our product.
In reality, less than 1% of our customers used the API at all. A portion of those who did were the most demanding customers we had, constantly complaining on social media that our API didn't support everything they wanted from day 1. Ironically, the most vocal API-using customers were more negative than positive for us. The extreme fringes of the DIY hacker communities can get very entitled and ugly.
Creating and maintaining the API was more work than we anticipated. With every new feature we had to make the decision to exclude it from the public API, or spend 50-100% more time integrating it into the next public API release cycle.
Overall, it doesn't make business sense to create an API if it will only be used by <1% of your customers. The only time an API makes sense is if the API will really, truly, genuinely be used by a significant portion of your customer base.
As techies, it's easy to forget that tools like IFTTT aren't mainstream outside of technical products. They're actually extremely obscure for the vast majority of the general public.