I told someone recently that I was working on a project to improve consistency among some web-based applications. Their response was, paraphrased, "It's boring when everything looks the same." And that's true, it is boring when everything looks the same. And even harmful, if the things that "look the same" behave in different ways or mean different things. Useful consistency comes from an agreed-upon set of rules for presentation and what that presentation means. If the layout of two pages are the same, it's done for a explicit reason. If the layouts are different, that's for an explicit reason.
I think I need to find another word besides "consistency," since nearly everyone I talk to understands it to mean "look the same."