Ladder is fine I just get bored of the same maps over and over again I'm 900-ish 1v1. I prefer Mapgen keeps it fresh.
The BO argument doesn't really bother me. I don't have any map specific BO's just generic ones, I don't think they really dictate the out come of the game that much as long as the opponent understands a generic one and all concepts in the game.
The rating argument, 1v1 vs global, I believe is more of a playstyle difference than who is better or which holds more weight.
The best way I've heard it explained talks about player map responsibility and how 1v1 rating doesn't always translate to global and vice versa.
My suggestion would be make a second 1v1 que which is only Mapgen and changes weekly. Do it for a month and see which que gets played the most. I believe that its a foregone conclusion that the map gen que comes out on top(happy to be wrong) but it would be an interesting experiment in any case.