Industrial Ecologist with a degree in Mechanical Engineering. It would seem, from my perspective, that the principal reason for using TeX is to annoy one's colleagues. The secondary reason is to provide procrastination activities. I am the last surviving user of PStricks (and, by extention, plain-LaTeX). I have never run pdf.*tex nor usedpackage pgf or tikz. This makes me a curmudgeon, even by LaTeX-user standards.
I filled out this section expressly to earn the "autobiographer" merit badge. BTW- merit badges and reputation? I feel like a cub scout playing Zork.
Maybe there should be a "shooting yourself in the foot by insisting on using obsolete packages" merit badge.