Allow me to list a few reasons I run with JS disabled by default:

- Poorly written JavaScript that causes my system to stall for a time, to the point where I have to kill all my browser's processes manually; more common than you'd think.

- Websites that attempt to mine cryptocurrencies using my browser with JavaScript; without my knowledge or permission.

- Then there's XSS and CSRF vulnerabilities that can leverage JavaScript to hijack active sessions.

And I am probably forgetting a few more reasons..

I do enable JavaScript for specific trusted websites, and I make temporary exceptions every now and then if necessary. But, I usually try to keep the list of exceptions short.

In regards to needing JavaScript for styling / design purposes.. Are you sure you need it? It might take you a bit longer to tweak and restructure the HTML and CSS to accomplish your design without JS, but it's well worth it.