There are some features that are provided in the paid version only. They are not a part of the free version. It would be good if some of them could be added to the free version as well to increase usability. If they did that, more people would go for the free version and it will help them explore all kinds of paid services and paid features at no cost. Likely, this would drive adoption and help them acquire more users.

It would be ideal if they could add support for rare services as well, to make it so that you can get a response both for SOAP and REST services.