And there's America's Got Talent and Britain's Got Talent. Almost same name, but different countries.
This kind of stuff has always been done and always will be done. Unfortunately, people saying they're not happy about it won't really change anything.
It's pretty much like when they remake older movies. Although sometimes the names are kept the same, sometimes they're not.
I think it's just expected that the only people who will notice are the people who have seen the old version. And since Americans don't watch British TV (it'd be rather difficult, although we might get a few shows, I don't know), they're not expected to notice it or have a problem if they hear about it.
I would think that whoever decided to do Leverage asked permission from whoever did Hustle, unless it's not something that is mandatory to do.
I'm not trying to diminish what you're saying or anything. What I stated was just my view. =]