It really depends what you are working on.
If you have to create forms every now and then or you have very weird layouts for forms, doing it direct in HTML5/BStrap is perfectly fine.
However, on flip side, I'm working on issue management portal, and we add and change forms quite often, but they are usually very similar from visual point of view.
So I ended up writing little form library that takes configuration, like input label, input name, type, if it's optional or required etc, and that library then produces that HTML for me - not just input tags, but whole divs and labels around it.
Saves some time if you have validation rules in models, for example, but you want to quickly mirror some of these on front end as JS checks, much easier than having to add this manually in every single time something changes. Plus it's so easy to forget to change front end if back end rules change, so less places to change is always better.
But using HTML is perfectly acceptable and quick way to get things started.
