A shameful death unlike Revan? Hmm, first of all we don't know if Revan died or not. For all we know, he died after a pazaak player got pissed that he lost and killed him for his credits back. Secondly, Vader realized his wrong doings and at the end of the movie, we see him in spirit form next to Obi-Wann and Yoda. That's shameful?