When this feature was released in 2012 I found it to be very useful. In my auto response emails I tend to have a a variety of links to continue engagement and I found the visual click-thru map to be very informative to which assets/topics are most popular and that would help me in buidling out new campaigns and fine tuning nurture streams.
I understand from Tech Support that this feature was disabled and no longer on the road map. Please vote - I really miss this feature111