Why you shouldn’t decrease your data-ink ratio.

Following Tufte's advice, I greatly decreased our chart's data-ink ratio.  I think you got that backwards.

From Edward Tufte’s The Visual Display of Quantitative Information:

A large share of ink on a graphic should present data-information, the ink changing as the data change. Data-ink is the non-erasable core of a graphic, the non-redundant ink arranged in response to variation in the numbers represented. Then,

Data-ink ratio

= data-ink / total ink used to print the graphic

= proportion of a graphic’s ink devoted to the non-redundant display of data-information

= 1.0 – proportion of a graphic that can be erased without loss of data-information.