It's just their aesthetic. I agree that it's a bit silly and not entirely functional. The larger wind cover will work but frankly I find it annoying to have to buy a new item entirely. Bear in mind that a lot of this is because of taller bowls. I use my standard or small Egyptian and the basic wind cover I have fits... barely lol.
When I use my vortex I have to prop the wind cover up until the coals die down a bit. If I use my funnel I need my largest wind cover unless I want to lock my tongs into the grooves of the stem and rest the wind cover on that.
Here is a visual reference to help you understand what I mean. I look ragged and disheveled in this video...