Because it's MY a$$ splattered all over the pavement.
Last I checked, the responsibility for MY a$$ was MINE, and nobody elses.

Edit: that was kind of a "do you still beat your wife?" question. I'm not taking responsibility for the drunk driver or his actions, I'm taking responsibility for my safety ("my a$$"). I am responsible to myself and my loved ones for my safety. If someone else wants to share in that responsibilty, that's great, but I sure as hell don't count on it. If a squirrel chews a branch off a tree that falls and whacks me on the head, it's nobody's fault but my own. Faulting a drunk driver for being drunk is like faulting a squirrel for being a squirrel. It's nothing I can change.

Edit 2: It's the drunk's responsibility to not drink and drive. It's my responsibility to stay safe even if he fails to meet his responsibility.