Has anyone noticed that the huge blockbuster video game sequels, Half Life, Portal, Halo, God of War, Mass Effect, etc have better stories and development then most blockbuster movie sequels?

I found myself thinking about this after completing Portal 2. I thought "now here is a game that not only brought back the things I loved the most about the first story but then made them better and expanded the story without it losing any of its original charm". How often does a movie sequel do this for someone? How often do we go to a movie and afterwards think "this was better then the original!" Usually we find ourselves thinking, "well it was nice to see the characters again and that one scene was cool" but overall the series lost a bit of shine that day.

Counter arguments may claim that games have a longer time to develop their stories and characters and while the games themselves might be longer I do not think a movie of the same caliber is incapable of doing the same for its own characters and story development.

Thoughts?