Sizing

What is with sizing these days?  Can the clothing companies just agree on measurements for clothes that are standard for each size?  I bought this top at Macys.com.  The color, called peacock blue, caught my eye along with the way it draped on the model.  It's kind of a slub tshirt material with dolman sleeves that drapes extremely well.  I know it's made to be oversized, but this was way too big (unless I wear it with a belt - hence the self-tie belt I added to the picture).  After trying it on, I packaged it back up for a return.  In the meantime, another wild sale hit Macys.com (or else it was just a wild night of shopping for me).  I went ahead and ordered the next size down in the same shirt before it went out of stock.  The original size was so large that I thought maybe I'd have to order 2 sizes down.  I received the new top today and it just barely fits.  There is at least a 4 inch difference in width between the two sizes (and that's 4 inches x2, so really 8 inches total).  It would sure be nice if these sizes were standardized!  But do you know what my dream sizing would be?  For plus size clothing to have a suggested shape, such as fits pear shape or hourglass shape, apple shaped, etc.!  Can you imagine how many less returns there would be?  Okay, okay, I don't suppose that kind of size-shaping will ever happen.