Heh, like Bumblebee's Ghost

Although I would take it on face value that it is actually Yoda's ghost. And being so powerful it really doesn't make sense. I mean, that super-ghost could single-handedly END the First Order and take out Kylo Ren. It makes Yoda kind of a <expletive> for not doing so.

The Force Ghosts made more sense in the Original Trilogy when they were just apparitions who only appeared to Luke and only he could see/hear them. And that's all they were... just voices and visions. They couldn't physically interact. From a story telling POV, it was so that these characters could continue to serve as the Hero's Mentor even from beyond the grave. And sure, Yoda does do this in The Last Jedi... but it could've also been done without the big extravagant destruction of the tree and books. It might've been better if Yoda had persuaded Luke to do it himself, thus allowing Luke to stop dwelling on the past and look towards the future. Not Yoda doing it for him.

One point that The Empire Strikes Back made was that if Yoda has to use the Force for Luke, then it was a sign of Luke's weakness or failure. Like getting Luke's X-Wing out of the swamp. Of course Yoda could've done it himself, but he wanted to get Luke to do it. And as a teacher (and parent) I can tell you that this completely makes sense. When my students or my daughter has a question or a problem to solve, I don't just give them the answers. I encourage them to work it out or discover it for themselves. I might help guide them to find these answers, but I really do not like just telling answers to kids because then they don't learn anything!

So Yoda was in full Teacher Mode on Dagobah when he initially told Luke to use the Force to retrieve his own X-Wing. Yoda only later did it himself after Luke had given up and told Yoda, "You want the impossible!" Then of course was the epic exchange after Yoda retrieved the X-Wing...
Luke: "I don't... I don't believe it!"
Yoda: "That is why you fail."

Yoda only did it as a lesson of last resort to prove to Luke that he was not asking for the impossible and that it could be done. Yoda was helping Luke to overcome his defeatist attitude. If Yoda wanted to do this again, then surely a similar style lesson would've worked better. In Empire, Yoda was more of a director of learning rather than just a prattling font of knowledge -- which is good teaching practice. A good teacher doesn't spew facts at you, they guide you to see it for yourself.

Seriously... The Last Jedi Ghost Yoda is like a freakin' Muppet Chuck Norris. He could totally end the Star Wars on his own.