PITTM,
I think analogies are useful because they use the same premises as the original event. In ethics you always have certain premises and be they in a certain hierarchy or proportionality. In everyday life people often rely on standard operating procedures which are derived from their ethical and moral premises and their constant exertion until they become SOPs, especially in situation when you don't have much time to think in order to seize the "opportunity".
When temporarily "borrowing" bandwidth is ok, why not "borrow" somebody else's money without permission? This example wouldn't be as farfetched as sleeping in a stranger's house, especially if it's just a buck or two... Somebody who's willing to go the first step is much more likely to go the second step, too, if he's being consistent. There's nothing wrong with being consistent but one might need to rethink the premises then. Unless I am completely mistaken, besides the different proportions, I don't see the distinct difference between borrowing somebody's money and borrowing his bandwidth without specific permission. Both money and bandwidth are means to certain ends that needs to be determined by the wielder. The point is not whether you think it might matter or not, the point is that every person has rights that need to be respected and you have no right to decide whether the other person may take use of his right or not; that's the point of having them to begin with.
Of course, it's not entirely black and white with moral standards and in some cases, a set of standards might have to be weighed against others or has to make room for a "greater good", which is to be argued, but even so I don't see the greater good in checking my emails using somebody else's bandwidth - unless somebody's life depended on it. There are no other moral obligations that would provide me with incentives to use his bandwidth either. Even if it was for the greater good, it'd still be a crime from a legal point of view, no matter how you look at it.
So propotionality might matter but it doesn't matter how grave a crime is (although it certainly matters for the degree of punishment); it only needs to break a certain law or somebody's personal rights as in this case to justify as crime. So is there a difference between using someone else's bandwidth and sleeping in somebody's else house? Certainly yes! Perhaps the Wifi owner doesn't mind and I'll happily chat with him about how to set up a protection barrier for his Wifi - but it's a crime nonetheless.
Of course, this doesn't even take into the consideration the Wifi provider's point of view as Born2bwire pointed out.
