You'll find that we share common properties a lot more for consistency, for example, the block padding and radius properties apply to various other properties themselves. If that doesn't suit you, then you may be able to use the extra box (though it's not necessarily guaranteed) or edit the CSS, yes.
Margins aren't editable in style properties as these represent page structure. However, we do expose the main "element spacer" margin under borders and spacing. (This also covers general paddings, for example.)