I think people are missing the point.
Yes, if you're working at McD's for 10 years and still making less than $8/hr you've clearly made some poor decisions somewhere along the line. But the point is, if we have a bunch of people trying to support themselves off that wage, then it's likely they'll be getting food stamps, bridge cards, welfare, etc. and putting more of a burden on taxpayers. Not to mention that it contributes to the excessive income inequality that we have (which is bad for the economy in general).
Not to say that people at McDonalds should be paid a lot, but I don't see why they can't come out of $10/hr. If they have to raise prices a little bit (not that they
really would have to, but..) then I'd say it's a worthwhile tradeoff. I mean it's not like people eating less fast food would be a bad thing.