Something that has been bugging me about the ending

Spoilers obviously.

Luke's 'redemption' and 'sacrifice'.

So Luke force projects himself - despite knowing this will kill him - in order to distract the New Empire but... how the hell does he know this will do any good? Am I missing something? The max he could hope to distract the bad guys was for what, 10 minutes? I mean that is one hell of a punt - to knowingly kill yourself to give your friends some time when they are apparently trapped and going to die anyway. And bearing in mind this is a guy who apparently 10 minutes before wasn't going to do anything to help. Now he's going to kill himself for almost no reason. Or are Jedi's psychic now as well, did he know that distracting Kylo would make a difference?

If he'd flown there physically it makes a lot more sense - he could fight, he could help, he could at the very least be with his friends at the last. But the whole hologram shtick just seems to be RJ having a 'gotcha' moment with the audience.