Two other topics that came up a lot at ESOMAR were respondent engagement and representativeness. Personally, I think discussions of the former are often misguided and discussions of the latter are a waste of time. Not that I oppose engaging respondents or high response rates, just that I'm practical enough to recognize that neither will happen without a good business reason for them to happen.
With regards to response rate, the boat has clearly sailed. Surely this is clear now that huge research buyers like P&G suggest moving beyond focus on response rate. I suspect they, like me, would love higher response rates, but they have come to realize that it isn't going to happen. The massive increase in the number of surveys being done (I get one every time I take my car in, and I was just handed on here on my plane trip back from ESOMAR) has caused the public to tire of doing them. Add in that improving response rates involves greater costs (more attempts, mixed modes, higher incentives) and greater time.