Not all of us fell into that trap! My dissertation was written almost entirely using a default document class and a handful of packages, and only towards the end did I apply the university document style to come into compliance. I had more than enough to do on the subject of the PhD and didn’t have the patience to burn time on typesetting or fiddling with macros.
I’ve found in the decades since then that my most productive co-authors have been the ones who don’t think about typesetting and just use the basics. The ones who obsess over things like tikz or fancy macros for things like source layout and such: they get annoying fast.
Tikz is misplaced in this list; it is how you make any kind of vector drawings in LaTeX. It's not the only way, but perhaps the best documented and most expressive one. If you have any such drawings in your work, you won't get around putting some effort into it. Not comparable with boxed theorems or fancy headings.
Tikz is sometimes useful, but it can also be a massive time sucking pain in the butt.
I mean it is one of the few packages that can actually manage to annoy LaTeX fans, which is really saying something.
I think the annoyance with TikZ is twofold: (1) it tries to do a really hard thing (create a picture with text in a human writable way), (2) it is used infrequently enough that it’s hard to learn through occasional use.
That said, nobody makes you use TikZ, fire up Inkscape and do it wysiwyg.