tChr... doesn't matter what the rules state. Nobody will want to play a 1v1 match with high ping, so that won't work.
For example, Kojn has told me that he won't play on an American server.
Bundy... There is potential for there to be more than 5-6 players in a North American ladder. In about a week and a half, I found about 23 players interested in the North American 1v1 tourney. Due to difficulty in scheduling and communicating, only 9 players appeared for the tourney. It's a lot easier to manage a ladder than it is to manage a tourney since there are no scheduling conflicts, so it would probably attract more people.
Also, what is the point of having everyone in one ladder when they have to avoid challenging certain players? Just split the thing up into two ladders.
The reason why i would like to see americans join "our" ladder:I think that it looks better for _now_
Perhaps you could make a push to get things moving on the existing ladder? I worked pretty hard to get the North American 1v1 tourney started. It wasn't easy but it happened. You could certainly do the same or better for a European 1v1 ladder, since you have more players to work with. It seems like the existing ladder is using the "if we build it, they will come" strategy.