What's your proof for Asura's descendants causing the three great wars?
And lets assume they did, then Indra's descendants were alive too during those wars. If they were so great why didn't they stop it? Or maybe they were weak and powerless compared to Ashura's descendants.
And the uchihas were responsible for their own destruction, first Madara damaged the reputation of the uchiha which made the village higher ups wary of them and then Obito unleashes the nine tails which further fueled the village's suspicion and then the uchiha plot for a coup didn't help either. If anything Indra's descendants failed at everything they tried to accomplish.
Real solutions like ruling the world with fear....

Go live in ISIS controlled parts of the world and then you'll understand how wrong you're.
And Ashura's line can't help it if Indra's descendants are not strong enough to see through their plans and always end up taking Ls from Ashura descendants. Ashura's descendants always end up clearing the bloody mess Indra's descendants create.