Their “dominance” is the choice of the distributions. Gnome is opinionated, and I respect that they follow their vision. To me this is free software working as intended, people are free to fork Gnome if they want something that the devs don’t want. And apparently, many distributions think Gnome should be the default. Maybe it shouldn’t, but that’s up to the distros to decide.
plain TeX is a joy to use, but you must really understand boxes and glue etc on a deep level. LaTeX makes that easier, but at the cost of extreme complexity internally (compare the output routines for example.)