ok well my question is, why give the eyes to the older son then? You make the rinnegan out to be a load of crap (dont try to backtrack, your convos on here imply you see the rinnegan as useless). The so6p beat the juubi through a combination of his powerful physical might and determination and his rinnegan eyes, of course the juubi still gave him power because he sealed it inside of himself. And just as easily as you tried to connect the eyes as evil because they came from the 10 tails (which led the older brothers lineage to be evil) it could just as easily be said that the eyes caused them to be evil because the eyes, granting superior power and skill almost from birth, allowed them to believe they were above everyone else, and they deserved power over others. While the physical power, allowed the younger brothers lineage to have the stamina and will to work for their power, hence they are usually innately good.