I often don't want to display widget headings, so I set them to ' ' (blank), but that still puts the H3 tag into the code and sometimes interferes with styling.
To allow further styling, I often create a text widget with its content wrapped inside a container with an 'id' or a 'class', which I then style. Very often, I include the H3 tag there too.
I suggest that widgets allow the assignment of the 'id' and 'class' attributes for styling purposes, as well as a tickbox for not showing the heading at all.