No, we don't need a dress code. But at the same time, no matter how much we pay for our tickets, and no matter how tired we are, the world does not begin and end with what "I am entitled to." I wouldn't bring a tuna sandwich on the plane because I am hungry. That would be unfair to others (not because I get to eat, but because the sandwich smells so much). When we share space with others, we should at least respect, and perhaps even set an example for, that person.
Now, this isn't to say that we should dress up. Jeans, even a clean t-shirt seem appropriate. But the sandals with no socks and the tank tops ... Well, my two cents.
[This message has been edited by zrs70 (edited 08-17-2000).]