Force projecting was in the Dark Empire series. They didn't just make that up for TLJ. They did their research. And ever since the beginning, we heard ObiWan say, "strike me down I will be more powerful than you can ever imagine"....and we finally get to see that!!!
I really feel like so many people have missed details either from the original films or from extended universe stuff. I am no expert at all on EU stuff, but its not hard to search and find out things. And not everything has to be spelled out for us to understand. Its like the originals left us with a lot of unanswered questions for decades. I mean one of the most beloved characters in the franchise Boba Fett was barely in the films, had maybe 5 minutes of total screen time and then died a quick death and people went nuts over him because in their mind they could picture the adventures he probably went on in his cool outfit. But who was he? No one knew back then.
today i feel like everyone just needs everything spelled out. They can't use their imagination anymore. If they don't see something on screen, then they can't understand it or grasp it. It wasn't like that with the originals. We never ever knew anything about the Emperor, how he came into power, how he was a Sith, nothing about him for like almost 20 years.