I use the back button frequently, and I don't believe it takes away from the game. When click the wrong link and lose the game, I don't want to go through the entire story (especially when it's one like Eternal or OTMS) to get to the same spot so i can take the different choice. The back button allows you to just click one button and keep playing the storygame, rather than having to play through the entire game again to make another decision, which would probably act as more of a deterrent than anything as it would just be a hassle to explore all the options.
TLDR: I don't want to get rid of it because I think it'll decrease efficiency.