After all this work, toil, sweat, blood, and tears, Moses doesn't get to enter the Promised Land. He can't even dip his big toe in.
What gives? Check out Moses's "Character Analysis" for more, but remember, keeping Moses out of Israel keeps him pure. These peeps are going to mess up big time in the Promised Land, and the writers don't want Moses to have anything to do with the flub. It might seem like a disappointment, but killing Moses off allows the writer to move on freely with the story while paying respects to the man himself.