Hmm. They do seem to have a more usable API, but they're going through this "MashApe" middleware to implement it. I've never used them before; I'll have to see what it involves.

Well, the more you are interacting with a group's service, the more you really need to get their approval and support. (It takes money to host a server and to pay for bandwidth, after all.) The source code I'm seeing for several of the MAL apps has a "configurable whitelisted user agent", which sounds to me like they've not been accessing the service in an authorized manner...

In any case, it'd be pretty easy to manage things like watched/plan to watch lists locally (if you really are in to that sort of thing). You could even combine anime data from multiple sources into a single app. It's just the social aspect that really needs a centralized server...