Nobody cares if matplotlib is outdated. It served its purpose here, which was to show how plotting data can lead to further understanding data. You don't need a fully featured tool to do so.
As far as "fully featured" goes, there is nothing more fully featured than matplotlib. It just tends to take a lot more code to generate a plot, compared to some higher-level libraries, so for simple visualizations, matplotlib may not be worth the tradeoff of power vs ease of use.
