But unless you're expecting only developers/programmers to use Trello, then saying "using the Trello API or just by appending '.json' to pretty much any URL" is basically worthless to most people. Our definitions of "very easily" must be enormously different.
True. On the other hand, it creates some level of trust since any programmer can now implement a Trello alternative for you to port your data to. So making the data available removes a lot of the lock-in. Of course, if the data can be exported in a format immediately usable by an application you already know such as some form of calendar this would be better. But I don't know of an application that overlaps sufficiently with Trello to capture the whole experience.
But unless you're expecting only developers/programmers to use Trello, then saying "using the Trello API or just by appending '.json' to pretty much any URL" is basically worthless to most people. Our definitions of "very easily" must be enormously different.