A small, but important aspect of typesetting/WYSIWYM is the ability to break down a large document (like a thesis) into discrete sub-components. You could work on each section of your document in an individual .tex file and include it later in your top-level .tex file. This setup works well with VCS like git.
Another ergonomic benefit is scripting. For example, if I'm running a series of scripts to generate figures/plots, LaTeX will pick up on the new files (if the filename is unmodified) and update those figures after recompiling. This is preferable to scrolling through a large document in MS Word and attempting to update each figure individually.
As the size and figure count of your document increases, the ergonomics in MS Word degrade. The initial setup effort in LaTeX becomes minimal as this cost is "amortized" over the document.