I'll be honest, I don't know where this everyone thought George had some grand plan has come from. When I say Disney needs a plan, it's inevitable that someone chimes in with "well George didn't have a plan". But he absolutely did have a plan. As I said it wasn't for some cinematic universe but it's there. I've never advocated that he wrote all 3 films first.
It's very well known he wrote a basic story and realized he couldn't make the whole thing. He broke it into 3 parts. There's a reason it all started with ep4. That's absolutely a plan. It was enough of a plan that he knew that there was a ep1-2-3 and ep7-8-9. All he had for those is rough story points but that's still a plan. Something he knew he could come back to. Again he had no idea he would even get a 2nd movie. Hence it was just star wars when it released.
Disney 100% purchased it to be an ongoing franchise. And in order to do that successfully, you absolutely need a plan. Otherwise you end up with DC instead of the infinity saga.