Should comicbook movies always stick to the source material?

It's a well known fact that almost every comicbook movie veers off the source material at one point or another. Sometimes the decision to do this is good, it benefits the story and helps the movie move along quicker. But other times these changes can insult fans and result in the loss of viewers.

At one end of the spectrum we have Blade. A comicbook anti hero that debuted on the big screen in 1998. In the comics Blade was not a half vampire or dhampir but was just immune to all types of vampire bites because his mother was bitten just before he was born. He also was not a superhuman and relied solely on skill and his vampire knowledge. Enter the Blade film. It took the different interpretations of the character (ie spider-man cartoon and comics)and mushed them into a hybrid. Although the film was based more on original ideas and the spider-man cartoon than the comics. The film was a big hit, making Blade a popular Marvel comics characters and known world wide. The film was so popular that they changed comics Blade's powers to those similar of the movie.

However on the complete other side of the spectrum we have punisher: war zone. Puisher: war zone stuck ever so close to the Max series. In some shots Ray Stevenson looks identical to some of the cover art but people thought that it was just over the top, had unrelatable characters and had to much violence. Even some punisher fans criticized it. I personally enjoyed it and it felt like a Gareth Ennis story without the story.