Another compelling reason not to switch to Leica.
Assuming their image quality actually is worse, it just means Leica buyers are probably putting more emphasis on portability, precision, quality workmanship and exclusivity. I don't think anything has changed here in the last 100 years. And despite a low ranking, you'd be a brave person to say that Leica's produce inferior results. Therefore, what's the use of the ranking anyway? Are they really meaningful in any useful way?
Interestingly, the low marks didn't seem to have affected the brand's prestige or sales. The same might be said of Canon's marks vs Nikon. It would seem most people view DxO Mark as little more than a scientific curiosity. Not something you'd base a serious purchasing decision on.