According to a post from a Google engineer, intended to be private to the search giant's employees, the Google+ API was not ready at launch. Google's Steve Yegge also badmouthed the read-only, public API. When the company's new service was only two weeks old, I wondered whether the Google+ API was intentionally late. Maybe it was just truly late.
Here's the portion where Yegge focuses on the API:
Google+ is a prime example of our complete failure to understand platforms from the very highest levels of executive leadership (hi Larry, Sergey, Eric, Vic, howdy howdy) down to the very lowest leaf workers (hey yo). We all don't get it. The Golden Rule of platforms is that you Eat Your Own Dogfood. The Google+ Platform is a pathetic afterthought. We had no API at all at launch, and last I checked, we had one measly API call.
Yegge also has a follow-up post that warns not to take the post as a representative of Google. "I know astoundingly little about Google," Yegge wrote. "I wouldn't read too much into anything I said."
Nobody cares you are a platform until they use your product, and if you spend all your time building a platform, there will be no product to use.
A year ago we asked can a platform succeed without a popular service? Though we didn't answer the question, I think it's unlikely. However, Google+ is already popular. And a read-only API with only public content will not suffice when the platform is so focused on the circles, which are essentially private messages.
The Google+ team is likely working hard to create a complete, OAuth-enabled API. In the meantime, developers and users are itching to incorporate the service into their current workflows.