What is so complicated about multiple map pools? 1 more click in the UI. One could argue that it's actually the simpler choice. You know, a beginner gets some kind of information about the maps he is about to play without having to check a long list of maps to ban those he maybe doesnt like. But sure, most of the other benefits of multiple map pools can be also acquired simply by making the map pool bigger and increasing the number of bans.
I think a better way to weigh is simply to have two quite similar maps in the pool, say Arabia and Green Arabia. It gives some additional variety, and is kinda easier to understand for the probabilistically handicapped.
The above should be "weighted" more towards arabia. E.G. 1/4 of your games are arabia. Or the player can decide where to throw their extra "weight." For instance, right now we can ban some maps... maybe you could also increase the odds for one map if you give up a ban, say.
I think a better way to weigh is simply to have two quite similar maps in the pool, say Arabia and Green Arabia. It gives some additional variety, and is kinda easier to understand for the probabilistically handicapped.