I'm not sure that I agree multiple apps aren't simpler. You do have the same knowledge requirement, but when you go to perform a function, you have less clutter, and memory load, to deal with. Less to distract you, etc.

I do like the Einstein quote. You want things to be simple for the user (or group of users), but you need to ensure things aren't too simple that they lose the functionality. It's trying to find the right place on a continuum, not picking among two options.