Hmm the question to me is -> does the "form-ui" always remain ? because data-attributes are custom attributes classes are default attributes.
that's the actual big question. We're all lazy to some extent so using "what's there" is always a good approach, but is it possible that this will break by a version update ? that's the maintainability perspective .
Personally I'm not a big fan of DOM-attr-coupling. classes are good enough to me. but if you want to just check if things can/will break in the future or if you have to keep dead nonsensical tags in the code just because you made this decision.
Maybe someone else has a better opinion Tommy Hodgins ? I am in the end not specialized on frontend.