With your last paragraph there, you are hypergeneralizing. I posted a very explicit example of two directly comparable lenses. DXO Mark's tests demonstrate that in every respect except T-stop, the Nikon lens performs worse than the Canon lens (for the 600mm f/4 in this case). The D800 has a great sensor with great DR...but the lens tests (which have nothing to do with DR) demonstrate that even the 36mp sensor cannot help Nikon's current 600 f/4 lens design keep up with the Canon lens design.
Admitidly I'v not looked much at the samples from super tele lenses and Canon may well be along way ahead there.
The PROBLEM, here, is that Nikon's lens was "scored" the same as Canon's lens. Given the raw data, the Canon lens should have scored better, without question. That begs the question...why? The only edge the Nikon 600mm had was 0.1 T-stops better transmission. So, DXO is really telling us that the end-all be-all of optical quality is having a tenth of a stop better transmission? Seriously?
Again I can see the worth of measuring the whole package although it obviously means comparing lenses will be harder.
There is clearly something wrong with DXO's scoring. Their lens tests are unabashedly biased, which makes you question every single one of their scores, and to some degree their approach. That's all I am saying. I'm not making any comparison of the general accuracy of DXO vs. DPR or anything like that...just saying that DXO has a severe and blatant bias, and people who use their information need to be aware of that.
Not sure where I stand on the "bias" but to me DxO's "pro Canon" P-Mpix score seems much much dodgier than there "anti Canon" DR scores. The methodology of it is only vaguely hinted at and all we get is a headline score that doesn't even state how its achieved(one focal length? an average?). The results disagree with my own viewing of sample images as well, the D800 has a much larger advantage in resolution than these numbers hint at. I see no such discrepancy with the DR figures where the Nikon cameras clearly do outperform the Canon's in recovering shadows at low ISO.