Why is TeX such a mess?

The simplest, modern route to using T_EX is to download TeX Live, but it's such a huge mess. Even the lightest installation can be hundreds of megabytes, and there are so many files it needs its own package management system.

Why can't I just download pdftex and run pdftex foo.tex and get a PDF? Why is there so much cruft for what is supposed to be ``traditional'' UNIX software?

You would think that TeX's idiosyncrasies makes it mostly a useless piece of shit that has no place in the modern world, but sadly there is no other markup language you can easily embed that matches it in its functionality. Yes, I'm looking at you microshaft, and your shitty ``Equation editor''. But, for anything else it's highly useless, so I wrote my thesis in goddamn Microsoft Word, and put in my overtly complex mathematical equations in by writing in TeX, saving the code separately and exporting them as images to the Word document. First class honours, by the way.