Interestingly enough we were split on this decision. We had a few people who thought we should go a straight scripting/API route and our own intuition saying we should add structure through our interface.

In the end we've tried to support the best of both world. You can add your endpoints using our interface and drop down to a scripting API (Javascript) to have fine-grained control over how we prepare requests/responses to and from your server. This gives you a lot of flexibility if you want it but it's not required.