* The designer did it, not me!
* I argued with him for months and ended up saying "ah, screw it".
* Ubuntu and Gnome do it too!
I don't see any of these as exculpatory. Not that what you've done is necessarily wrong per se, I'd just rather you come by it honestly. I don't think any of these designs (or for example some of the icons - or even the decision to group elements into these categories) are "inevitable".