John Doom said:

I still think throwing away his lightsaber was foolish. Even if Yoda and Obi-wan weren't able to train him to stand against the Emperor, I think it would've make more sense if Luke had done his best to defend himself, even if eventually losing. And THEN have Vader save the day and redeem himself.

The way Luke throws away his lightsaber looks like he's ready to die like in TESB, instead of actually giving his life to save the galaxy (like Vader later does).

You missed the point. By fighting Emperor he would not to save the galaxy. He would just go along with the Emperor's plan. If he fought him he would fall to the dark side and instead of saving the galaxy he would become Emperor's tool.