Rejections based upon "mere design choice"

The 717MadisonPlace blog notes the words of Judge Linn on "mere design choice" -->

I can remember way back when when I was an examiner, some of the toughest problems we faced were when we went out, we did comprehensive searches, and we found references that covered every element of the claim except one little thing. And, it was common practice back then, and I think you’re justifying the practice, that the examiners very frequently would say ‘Well the claim is rejected A in view of B and C — with respect to the last element, that’s a matter of mere design choice of no patentable consequence.’ It was a nice phrase. It had a nice ring to it. But I often wondered whether that was legitimate or not.