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.