Passports

I just do not understand the point of passports. I know that obviously sounds like an unintelligent comment, but I just discovered on my way to Mexico that you are unable to leave the country if your passport is expired (mine expired 6 days before I chose to leave). Why can’t I leave the country with just proof of citizenship and my birth certificate; he law was just changed in January of 2009, which makes it no longer acceptable when flying by air. I know that Mexico is a rough place these days, but I think it is pretty obvious that I am just a Spring Breaker who does not want to permanently stay in Mexico. Also, why do they make it so hard to get a passport? I waited for seven hours in the passport agency just to get a small book with my picture that doesn’t really even look like me. I know that there are very good reasons for passports especially when travelling, but why does the government have to be so hard on their citizens? I also know this seems like a stupid complaint, why do we have to go through such a tedious process just because we want to experience something new? I do not think we should have to; as long as the government knows we are gone we should just be able to travel the world freely!