Similar to what Reven and Voei have said, once Optifine updates to 1.7 it really doesn't matter whether BSM is banned or not. If people are able to use 1.7 instead, that is equal, or arguably better to any potential benefits provided by BSM, and I doubt anyone will really continue to use it. But until Optifine is updated to 1.7, BSM is as necessary as Optifine for players with bad computers to have an equal playing field. So personally, I think it should be allowed at least in this interim period, as it IS required for people to play and still have a fair chance at winning if they are unable to update to 1.7. Once Optifine updates and/or BSM develops new features that provide an unfair advantage over vanilla MC, go ahead and ban it. In the first case, it won't really matter to anyone, and the second is only fair. But in the present time, I see no reason for it to be banned, especially when people require it to play.