actually if you look back to all the EU coverage "KOTOR 1&2" it works the other way round, the sith kinda wipe out the jedi! And when it comes down to the sith being in such small numbers, it was one of the older sith lords who enforced the "the rule of two" kinda like the "rule of thumb" but says theres at one point only two can exists "no more, no less"! But then thats all EU stuff which doesn't count if you look at it from a certain point of view!
Im just guessing there generally just moody. Maybe the sith kicked there ball over the jedis fence and they didn't return it *shrugs*