I can see the general strategy there though: it's easier to be excessively stringent then improve and relax through iteration and emergent discovery of use case

I can see the general strategy there though: it's easier to be excessively stringent then improve and relax through iteration and emergent discovery of use cases than the other way around. E.g accessing the filesystem used to be downright impossible in the MAS, preventing apps like Coda or DaisyDisk from even existing due to stringent sandboxing, but now it's perfectly possible.