Follow up from #1743686: Condition Plugin System. getConfig() and setConfig() are useful for all plugins where configuration needs to be gotten or set after plugin instantiation. getConfigDefinition() and getConfigDefinitions() are useful for all plugins that want to support configuration introspection UIs and APIs (like Rules does). None of this is specific to "executable" plugins.
This is also a good issue to further discuss the difference between runtime swappable configuration and context, since these methods currently overlap quite a bit with the various context related ones. In Rules, there is no difference. But in Blocks, there is. There's a little discussion of this in the original issue, but I'm not up to speed enough on it to summarize that here. Someone who is: please do.