This looks great, and very tastefully implemented on the Clojure side. Have you considered splitting out things like the quil utils?
Currently, I do not have resources to take on the task of creating a general-purpose plotting library. My idea with the plotting toolbox available in Bayadera is to provide a tool that would do one job - provide fast, easy to use, plotting for exactly those types of plots that are needed for bayesian stuff - and do that job well.
Plotting in general is not that hard technically, but the problem is that each user in each situation wants something unique. The level of customizability found in ggplot, matplotlib and the likes is rather high; that's something I do not have motivation to pursue.