Working for Envato, I’ve seen a fair few trends come and go, and whilst I’m not a web-designer by trade, i’ve certainly got a bit of exposure to the industry and I’m no stranger to building a website with WP.
The main thing that I’ve noticed is that web-design trends are led by innovations in usability. Form follows function. Whilst a lot of pro-designers might nitpick on the way an image is presented or a font choice, I would argue that A website begins to feel “dated” when it falls behind in terms of how a user can navigate it and source information compared to the norm. “Minimalism” (as an example) was in vogue because it cleared away clutter and made the sites easier to navigate.
As an example, yesterday I found myself swearing at a restaurant website on my mobile phone because whilst the site was responsive- it’s menu wouldn’t allow me to zoom in, making it’s contents illegible. That’s a dated website design.
Naturally it also depends what your trying to achieve. Brutalism is a very effective way of getting a very specific reaction out of a visitor, but it won’t work for everyone’s goals.