Well, there are different things, one thing is the issues we had in this gameworld, another thing is what you mention TeutonicG.
We have 3 tribes because it is the most balanced thing to have. Throwing in new tribes and making it unbalanced doesn't benefit anyone.
make some servers that are unbalanced and fun, whit new tribes ect. you guys didn't have any problems last haloween to give bats and spiders a huge deff value buff.