Earlier quoted context omitted.
This is just unfamiliarity IMO. This is a component you reuse across tons of sites, it's not a one off component you're building for yourself. It's also not just a CSS framework like Bootstrap. This is full CSS + JS component's with functionality, Vue/React/Svelte framework integration, and events built in. Whether css-in-JS as a whole makes sense beyond these generic component type systems is a good question. There'…
Bootstrap has JS components. And utility classes.
Unless they modernized it in recent years, haven't used it in 5yrs.