1967 was an era of tank-power, of the Cold War, of an Israel that was still comparatively young and vulnerable. Today, Israel is the regional military superpower in an era of missiles and hi-tech. It's perfectly capable of defending the 1967 borders. It might prefer to defend a whole chunk of the West Bank, but it doesn't NEED to.
Zimbabwean charged over killing of Cecil the lion (Reuters)
from the article: Setting Palestine's borders