Some problems: the colours are not that great, and also not colourblind-safe. And most grating of all: why are the tics light gray and not black! It's very hard to read.
Just curious but why go for gnuplot (and awk) rather than python or R? At some point you run up to some limit where you want a bit more capability. I don't know that the learning curve is that much less for awk + gnuplot?
Gnuplot (and awk) have several advantages. It’s faster, especially for large datasets; it’s language-independent and can be used through pipes with any language, so the plotting solution you develop can go with you as you change your simulation language; it’s designed to be automated, plot over the network, etc.