It's not just aesthetics, having proper typesetting makes papers more accessible, easier to read and parse, the standard formatting makes understanding the layout of papers easier, there is a huge library of packages that cleanly abstract the task of rendering obscure symbols and complex mathematical formulas, and it automates the job of tracking figure, equation and reference citations to name just a few of the features. Fine, TeX is an ugly language that only a programmer could love, but in over twenty years nobody has yet been able to replace its expressive power and flexibility -- doc generators just compile to LaTeX and more user friendly GUIs like Lyx and TeXMaker have been written to ease the process of writing for end users, but the underlying format has yet to be replaced in over twenty years. Like Markdown, TeX rides the line between being able to be written by hand for greater flexibility and automatically generated for newbies.

Unless you think that reading red text on a blue background in payprus would be an equally enjoyable reading experience it more than simple aesthetics.