I think it's kind of funny tbh.
I guess every actor has done a part they weren't particularly fond of, pretty awesome career if Star Wars was your low point.
I am pretty sure Sir Guiness did not hate his role initially, but became tired with being associated with that role at the expense of his other roles. In fact I remember reading that Sir Guiness was disappointed that he was killed off so early in the film and tried to talk George Lucas out of including Obi-Wan's death in the script. Instead he got to return in the sequels as a spirit. He did not "hate" Star Wars, Sir Guiness just got fed up with the hype surrounding the role he played.
Well from what I read about Alec was that that he began to hate the role because the fan mail he was receiving was all about star wars. He did not want his other roles overshadowed by playing Obi wan. He has done some great acting in other movies. I would probably feel the same way if i were him.
Never do understand why actors do that. They get paid more money than the rest of people out there and then bash the movie their in and say it was terrible. I read several of his quotes leading up to his death. I was shocked and appalled by his statements. I lost respect for him. He became a bitter old man in old age. I expect more out of Brtish actoor especially after he played in some good moviesin the 50's and 60's.