Being able to think "Hmmm, I want a rounded button, with a border and a blue background" and just typing class="rounded border border-blue-600 bg-blue-500" and it's done.
With lots of UI being components now, it doesn't really matter that it is verbose - I actually find that helpful. And even if you want to have a class that you use all over the place, just use @apply and create a custom class that you can use anywhere.
One place it can be hard to use, is if you have a specific design system - then yea at that point you either work with Tailwind and modify the config to match, or you just go with standard CSS - but at that point it probably makes sense.