Lots of things changed since then -- that's not a particularly strong argument. Back then there were no nontrads, there were no non-science majors. Pretty much everyone was a bio major. Medical schools have gone thru a huge transformation in terms of what makes a good doctor, and more or less have rejected a lot of the traditional notions. Hence the interviews, the emphasis on uniqueness, well rounded-ness, the enrollment of an ever growing number of humanities majors, the not going strictly by the numbers. So I wouldn't use what used to be as a particularly strong argument as to how to determine how important to consider the interview today.
I know quite a few people who vaulted past folks with higher stats thanks to the strength of their interviews. Far more than the supposed 10% happydoc suggests (unless the folks I know are totally skewed from the norm, percentage-wise). I'm sure it varies from place to place. A few schools actually will tell you that nothing else counts once you get to the interview stage. So treat it as a significant part of the application process, and prepare accordingly.