In the new version of ATK 12.2 matplotlib has been updated.
In general we try to be progressive when it comes to the packages we ship along and use internally, but sometimes we encounter problems with these, and we have to fill bugs reports to numpy etc, and it is not always that these get fixed on all the platforms we support before a release. Our aim is to have the latest stable version of all our packages as long as it runs on all the platforms we support.