You make a good point. With all of the display variance out there, it's quite likely that some displays are so out of whack that calibration isn't an option. In my case, I was able eliminate the yellow tint to bring my display in line with my 27" iMac with only a 300K increase toward blue. I was actually surprised that such a small color temperature adjustment made such a big difference. This was all done by eye, so it's entirely possible that my iMac is too blue to begin with (I'm just using the default calibration on it) and my rMBP was where it should've been. I've got an X-rite i1Display Pro on order so we'll see what "reality" is tomorrow once it arrives.This is not a debatable slight tint. I tried (and failed) to correct using the built-in advanced calibration settings, the best I got (without fixing the uneven brightness and color shifts) was about a 800 Kelvin increase (= towards blue) to get rid of the yellow elements of the tint (it's not pure yellow, which why some on the forum have referred to it as pink, perhaps on displays with even more extreme variation).
I guess the overall point I'm trying to make is that it's very unlikely that anyone will get a "perfect" display (one person above went through 7 exchanges before getting a display they were satisfied with!). If your display is good (no dead pixels, even color/brightness uniformity) and the only issue is a slightly yellow tint, it might behoove you to calibrate the display rather than going through the hassle and pain of numerous exchanges.