iOS was never particularly cohesive. App icons have always been a mixed bag (gradients, lighting, gloss, dimensionality). I don't see iOS7 as a particular departure from this. Also, if things are too minimal and cohesive, the UI becomes very boring. I can't imagine ever being excited about a UI that was universally designed like the new Mail app you praise.

One of the things that bothers me about this post and others like it is that it has an element internal inconsistency. Having the entire UI unified and minimal as you suggest does not strike me as relying on intuitive or emotional or human design. It strikes me as being over-engineered and analytical.