xterm's support for the Tek graphics terminal is actually quite neat, since you can use it with for example gnuplot to plot things over a (bad) SSH connection.
Also there is still some niche software that still requires it (for example IRAF which sadly is still going strong in the astronomy community).
Indeed it is and not just for that. When I developed the firmware for our my company's laser product I exhaustively used the Tek graphics support for debugging purposes. Kind of neat if you've got only a serial connection and have to plot graphs. Much better than dumping it into a file and plotting it with gnuplot.
Also there is still some niche software that still requires it (for example IRAF which sadly is still going strong in the astronomy community).