- The xml elements from the API that use the key (please see the URL above) are surrounded by a "response" element in XML representation. Why? We all know that is the response...
- The representation of the resource in a page that use the page open API (try http://steamcommunity.com/id/jesuino?xml=1) has two main issues: 1 - representation information in URL and 2 when you access a non-existing account the reponse from server is simply a new representations instead a 404 (try http://steamcommunity.com/id/NO_EXISTING_ACCOUNT?xml=1).
Today we have the Richardson maturity model and a lot of learned lessons from past, but some APIs still born with issues in design.
While we can consume and we have a lot of clients using an API, it will exist even if it has some design issues. A lot has been done in community to spread the real REST principles, but bad designed APIs are consumable and we can build applications using it.
So what is the best motivation big services have to start to create a really RESTful app?
Sure we can list some advantages of using RESTful, but seems sometimes some RESTful APIs creators think like "it's working as it it,so let's keep this way"