Hollywood and Bollywood getting inspired by EAST

Recently i saw two movies from east, which are now remade in Hollywood and Bollywood. After watching all these originals and remakes i had this question in my mind, what makes a good remake?

The movies i am talking about are OLDBOY(2003, Korean) and MOU GAAN DOU(2002,Thai). "OldBoy" is remade in Bollywood by the name "Zinda" and "MOU GAAN DOU" is remade in hollywood as "The Departed".

All of these movies are good, but some are better. First take the case of "OldBoy", which is made in bollywood by Sanjay Gupta. He chose to copy each and everything from the movie(Though he claimed that he is only 'inspired' by korean movies) to create the similar suspense and spine chilling effect(really??) but in the end he decided to move away from the climax because that might not be acceptable in Indian cinema. So, he gave us the same movie in hindi with good acting performances BUT the intensity of climax was nowhere compared to original one and that one thing makes it much inferior than original because he missed the point altogether.(similar blunder was committed by Vivek Agnihotri while making "Chocolate" which is copy of "usual suspects" )

Now the other movie Mou Gaan Dou (aka Infernal Affairs) which was so good that it has inspired a director like Martin Scorsese to make it again. He chose to take the events and story of movie and added his ideas to make it more understandable and relevant to the American society. Original movie is very fast paced and has some marvelous acting performances but i seriously doubt that a person can understand everything in this movie, because the director didn't stop to explain all the reasons. Scorsese added that logic to the film and thus made it more acceptable to the American audiences. The Departed has all the thrill of original movie, equally good actors but a much better director.

I wrote what i thought about remakes, but i would like others to comment on the same. If you have not seen these movies then go and watch, at least "Old Boy" and "The Departed".