Can't offhand think of any convincing cons – inter-paragraph spacing should be controlled by styles, usually spiced up with a dash of Keep with next.

Isn't/wasn't there an issue when a paragraph with space before in the style ended up at the top of a page? I've seen it referred to in the helps for an Open/Libre Office compatibility setting, but don't remember which side of the fence it fell on. I don't have 2003 to check.