So Yoda and Obi Wan send Luke to face Vader and the Emperor, but they forgot to teach him how to block Force Lightning?? Dropped the ball a bit there guys.
Nah, Luke was hangin' on Dagobah chatting with Ghost Ben before he went off to face the Emperor. Plenty of time for a few pointers there.
I think Yoda was even taken by surprise by Palpatine's lightning in RotS, don't recall if Yoda deflected it later on in their duel though. I think in context to RotJ Palpatine's (or back then, simply the Emperor's) lightning was supposed to be a surprise to the audience, as well as Luke. But in the grand scheme of things, you would think Yoda would have tried to prepare Luke for what the Emperor was capable of. Yoda warns Luke about the Emperors power, or Luke will suffer his father's fate, but it seems Yoda might be referring more to the Emperor's power to manipulate.
Dooku seemed rather surprised Yoda could even do that. Clearly it's not something even experienced masters are able to do, much less a poorly disciplined wannabe who's had a sum total of 1 very brief lightsaber lesson/lecture from an actual master, three years prior to showing up on Dagobah. Yoda was still trying to teach Luke fundamental control and inner peace: the kind of thing most Jedi get a handle on by the time they're taken as Padawans. They weren't anywhere near that level of force discipline.
Yoda didn't block Force lightning, he absorbed the energy, held it, and redirected it - an ability that was not common among Force users. Luke may not have had that inborn ability.
It was thought up, as you put it--even to the point where Luke was able to temporarily deflect the Emperor's lightning...in the Return of the Jedi novelization.
Probably never occurred to him that Luke would just decide to chuck his lightsaber half way across the room, and assumed Luke would reflexively block with that method. Luke Skywalker: Maker of wise decisions since 1977.
Luke had abandoned his training with Yoda about a few days or a few weeks after he had started. Remember? And do you remember that Luke didn't bother to return to Dagobah? Which EU novel had confirmed that this ability of Yoda's was inborn?
Yes, he was wise in the OT when he let himself fall to what would have been his death, instead of joining the dark side, and yes, tossing his lightsaber aside as a show of his complete rejection of said dark at the most important moment of the SW films.
You can't teach to block what you yourself cannot (or dare not) demonstrate. As SPCTRE's picture indicates, Force lightning is as Dark Side a power as they come - literally pouring every ounce of your hatred at your opponent. That's not Yoda's way. Yoda and Obi-Wan were training Luke to face and destroy Vader - that was their priority. The Emperor was for much later down the line, if at all. If even Yoda could barely eke out a draw with that monster, what chance would Luke have anyway?
I don’t actually care about whether you found the scene ‘powerful.’ Even if I was actually reviewing the scene or gave any sort of opinion on it whatsoever (which would have made your comment relevant at least), I still wouldn’t care. Because I wasn’t asking a question. I was replying to one. So that’s why he fled to the edges of the universe. He never improved past ANH, and that little training robot spent decades chasing him and trying to shoot him in the ass. Windu implies in TPM that there hasn’t been Sith in his lifetime. As in, he doesn’t even think hey exist anymore. He’s wrong of course, but that hardly suggests that he’s had a lot of practice fighting them. Also, the movies don’t have ‘Dark Side powers.’ That’s thankfully gone the way of the old EU. Movies just had it that good people don’t use their lightening or telekinetic abilities to do bad things zap and choke people. Highly-invasive telepathic mind fuckery on random civilians, on the other hand? Well, that shit’s just peachy. Such a good guy move, that we never really see the villains use it!
But he didn't complete his training in TESB where Yoda maybe could learned him to block force lightning
Then he was apparently blind during all those lessons. Because as Yoda mockingly points out, Luke’s ridiculously shocked to see that Yoda has rather notably aged since he last saw him. Yoda: That face you make... look I so old to young eyes? Luke: No. Of course not. Yoda: I do. Yes, I do. Sick have I become, old and weak... When nine hundred years old *you* reach, look as good *you* will not, hmm? So either Yoda aged to death practically overnight, Luke’s a particularly ignorant dunce, or he was just gone for a while trying to save Han. It would also mean during all those lessons, Luke just randomly decided to put off fact-checking Vader’s fatherhood claim until after he saved Han.
Yoda was old even before the events of Episode I and was starting to show signs of infirmity towards the end of the Clone Wars. I think it's pretty clear that just as the likes of Vader and Maul clung to life when their bodies should have been beyond repair through sheer will and hatred, Yoda was holding onto life long enough to achieve his purpose. So when Luke truly started to come into his own, he was able to let go and allow his body to perish. If nothing else, over 20 years surviving alone in the wilderness on a bog planet couldn't have done much for his health. I mean just look at what it did to Obi-Wan!