If places like Disneyland and Studios couldn't even fill their SW lands with guests when using one-fith of a park how in the world could a park solely dedicated to BB8's and Yoda's be a "world wide hit" ?
Well, it's an original land (i.e. not an iconic location) with only two attractions set entirely in a time period that was not remotely close to being universally loved. Not that Galaxy's Edge is bad -- it's just not the home run a Star Wars land should have been. A full Star Wars park that had areas based around famous locations and could more easily use characters from all Star Wars eras in attractions etc. would probably be a much larger hit.
I'm not arguing that they should build a Star Wars only park, mind you -- I don't think that's a good idea. But they could easily build something that was more successful than Galaxy's Edge.