I went on 16 interviews and the subject of Step 2CK was brought up exactly once, at my very last interview (in early mid-February). And even then it was just "so, did you take Step 2?" and I said "yup, my score was ____" and the response was "oh good, seems like everyone today has gone up from Step 1, that's nice to see." And I had only gotten my score back a few days prior (I took Step 2 in late December).
Most other people I talked to had not taken Step 2 at the time of interview season (and the ones who had seemed to indicate that they had done so to make up for a less than stellar Step 1). My goal in taking it in December was to be able to have the score back prior to rank lists being due, but opting to not automatically release it right away to programs (so that if it came back as a poor score, I could choose to delay it until after ranklists were in, and if it came back high, I could release it before schools ranked applicants). Sure, some programs probably ranked us right after the last interview and never looked back, but it was a chance I was more than willing to take.
Even one of the programs that explicitly stated on their website that one must have taken Step 2 prior to November 1 in order to be considered for an interview offered me an interview (I think the offer came mid-November) before I had ever taken the test. So even for them it was not a hard and fast rule.
Whoever said that 70% of program directors surveyed said they require it should go back and look at the sample size in those surveys. If I recall correctly, something like 25% (at most) of all program directors were represented in that survey, so the numbers are not quite so impressive.
So, maybe I just lucked out and the 16 places that offered me interviews were some of the only programs that didn't require Step 2 before offering interviews, but judging by what I saw on the interview trail, I agree with drdan that more often than not it seemed as though people had put the test off.