Update: I've decided to switch back from xhtml to html and add a sprinkling of styling elements here and there. Xhtml is just a little bit of a pain in the butt, and there are a few tweaks I wanted to make that wouldn't be possible in pure xhtml with no styling.
I feel the need to preempt this question of "why is your website so ugly?". I don't want people to venture on to my website and think "wow, this guy has no idea what he's doing." While that may be true to some extent, I do actually know how to make a website look good. So, why is my website so ugly? Why not spruce things up with some images and CSS?
My website is the way it is as a bit of a statement. I really dislike the modern web. It's so unbelievably bloated. You really don't need a bunch of convoluted JS/CSS and several MBs of assets to do, well, really anything that you might need to do online. That's not to say you can't use any JS/CSS in a good website, but it's gone so far out of hand these days that I think I really need to just use none of it at all to get the point across. If you haven't already, go watch The Website Obesity Crisis . It's a great talk about just how fat the modern web has become (this was in 2015; it's only gotten worse in the intervening years).
An additional benefit to avoiding CSS and JavaScript it that it makes the website very easy to maintain. I don't have to worry about styles or positioning or anything like that. I can just put words on the page plain and simple.
In conclusion, I hate the modern web. I don't think that improved hardware means you should immediately fill those resources with useless garbage. JS/CSS should never be essential to the function of your website; it's seasoning, not a meal.