Why should we change our voting system?

As the referendum on the Alternative Vote approaches I’m getting more worried that the change will be voted out and we’ll be stuck with First Past the Post for another umpteen years. So I did a little xkcd-style cartoon to help illustrate some of the points and why, from my perspective, we should vote ‘Yes’. (With ‘No’ as second-choice, ha ha…)

The Alternative Vote has its problems too, but I see it as a ‘gateway’ voting system that might lead to proportional representation in the future.